Nutrition

Introduction

Nutrition describes the food and drink we take in to maintain our health and metabolism. Healthy nutrition results from maintaining energy balance with the appropriate composition of nutrients. This is critically important for all aspects of metabolic health and improving cancer outcomes. Let’s start with an overview of several key concepts in nutrition including energy balance, body composition and obesity and the impact of obesity on cancer. We will also review the concept of whole versus processed foods and how this impacts nutrition. This will lead us to an in depth discussion of the major dietary components including macronutrients, micronutrients, fiber and polyphenols that are important to consider when designing a nutrition plan. We will discuss different dietary strategies and the advantages and disadvantages of each. The goal of this section of the site is to help you begin to develop an individualized nutritional plan that meets your needs and minimizes the risk of cancer. We also include tools such as nutritional content tables and links to more in depth resources to help you navigate your nutritional journey.

Energy Balance, Body Composition and Obesity

Energy balance is the relationship between the number of calories you consume through food and drink and the number of calories your body burns at rest (basal metabolic rate), through daily activities and exercise. When you consume more calories than your body burns, you are in a state of positive energy balance, or energy surplus. This can lead to weight gain over time. When you burn more calories than you consume, you are in a state of negative energy balance, or energy deficit, which can result in weight loss. Maintaining energy balance over time is key to achieving a healthy body composition and metabolism.

Body composition refers to the relative amount of fat, muscle, bone, and other tissues that make up your body. Organs, bone and muscle are considered to be lean body mass. Fat is a storage form of energy that can accumulate under the skin (subcutaneous fat) or in and around the organs (visceral fat). The relative amount of body fat can be estimated by the body mass index (weight in kg / height in m2). Lean body mass and fat mass are more accurately determined with a Dexa scan, a low dose x-ray scan that measures body composition. People with a higher lean body mass have a lower risk of many diseases, including cancer. Those with a higher fat mass, especially more visceral fat, have a higher risk of most chronic disease, including cancer.

When you consistently consume more calories than you burn, the excess energy is stored as fat, leading to an increase in body fat percentage, or obesity. Conversely, when you create a slight calorie deficit through a combination of reduced calorie intake and increased physical activity, your body will burn stored fat for energy, leading to a decrease in body fat percentage. Engaging in regular exercise, particularly resistance training, can help build and maintain lean muscle mass, which is important for a healthy body composition and overall health.

Obesity is a serious health condition that occurs when a person has excessive body fat. It can have a significant impact on an individual’s overall health and well-being. The most common definition of obesity is a BMI of 30 or greater, while individuals with a BMI of 25 to 30 are considered overweight. The most accurate way to determine body composition is DEXA scan, where the definition of obesity is a body fat percentage of 25% or more in males and 32% or more in females. Obesity increases the risk of developing type 2 diabetes, cardiovascular disease and cancer. As a person becomes obese, their body becomes less sensitive to insulin. This is insulin resistance, or prediabetes. When this process becomes more severe and glucose levels rise, type 2 diabetes is present.

Obesity and Cancer

The risk of many common cancers is increased by obesity. For example, women who are obese after menopause have a 20-40% higher risk of developing breast cancer compared to women of a healthy weight. Obesity increases the risk of colon cancer in both men and women by about 30%. The risk of melanoma is increased by up to 80% in obese persons. It’s important to note that while obesity increases the risk of these and other cancers, it does not mean that all people with obesity will develop cancer. However, maintaining a healthy body weight through healthy nutrition and regular physical activity can help reduce the risk of cancer.

The relationship between obesity and cancer is complex and appears to occur through several mechanisms including:

Hormonal changes: Fat cells produce excess amounts of estrogen, which can promote the growth of cancers that are sensitive to hormones, such as breast and endometrial cancers.
Insulin resistance: Obesity can cause insulin resistance, leading to high levels of insulin and insulin-like growth factors in the body. These hormones can promote the growth of cancer cells.
Inflammation and oxidative stress: Obesity decreases mitochondrial function. This triggers a cell danger response that leads to increased inflammation and oxidative stress. These changes combine to alter metabolism and gene expression and cause DNA damage which can increase the risk of developing cancer.
Immune dysfunction: Mitochondrial dysfunction, inflammation and oxidative stress work together to impair the function of the adaptive immune system. This decreases the ability of the immune system to identify and eliminate cancer cells or keep them from growing.

Whole Foods and Processed Foods

Whole foods are minimally processed and remain close to their natural state. They include vegetables, fruit, whole grains, legumes, nuts, seeds, and unprocessed meat, poultry, and fish. Whole foods are typically nutrient-dense, meaning they provide a wide range of vitamins, minerals, antioxidants, and fiber, all of which are essential for maintaining optimal health.

Processed foods are those that have been modified from their original form to enhance flavor, convenience or shelf life. They often contain added sugar, salt, unhealthy fats, and artificial ingredients. Examples of processed foods include packaged snacks, sugary beverages, processed meats, and frozen dinners. While some processed foods can be part of a balanced diet, most are calorie-dense and low in essential nutrients.

The consumption of highly processed foods has been linked to various negative effects on metabolic health. These foods often have a high glycemic index, meaning they can cause rapid or prolonged increases (“spikes”) in blood sugar levels. Over time, this may lead to insulin resistance and type 2 diabetes. Processed foods also tend to be high in unhealthy fats, such as saturated fats and refined vegetable oils, which can contribute to inflammation and an increased risk of heart disease. The added sugars and low fiber content of processed foods makes them less satiating (filling) than whole food, which can lead to overeating and weight gain.

To support optimal metabolic health, you should prioritize whole foods in the diet and limit the intake of processed foods. This can provide the body with essential nutrients, promote satiety and reduce the risk of chronic diseases associated with poor metabolic health.

Overview of Dietary Components

Macronutrients

The three main components of our diet are called macronutrients. They are: carbohydrates, fats and protein. Each macronutrient contains a specific amount of energy or calories per gram: Carbohydrates: 4 calories per gram; Fats: 9 calories per gram; Protein: 4 calories per gram. Our bodies use macronutrients to produce energy through metabolism and build the cells that make up the organs and tissues in the body.

When we eat carbohydrates, our body breaks them down into simple sugars, mainly glucose. Glucose is the primary energy source for our cells. If we consume more glucose than our body needs immediately, it is stored in the liver and muscles as glycogen or converted into fat for long-term energy storage.

Fats are the most calorie-dense macronutrient, providing more than twice the energy per gram compared to carbohydrates and protein. They are an important source of energy, particularly during low-intensity exercise and at rest. When we consume fats, they are broken down into fatty acids, which can be used for energy production. Fats are essential for hormone production, cell membrane structure, and the absorption of fat-soluble vitamins (A, D, E, and K).

Proteins are critical for building and repairing tissues in our body. When we eat proteins, our body breaks them down into amino acids. Amino acids can be used for energy, but this only occurs when carbohydrate and fat intake is low, protein intake is very high or during prolonged exercise. The body prefers to use amino acids to build new proteins in cells rather than for energy production.

All three macronutrients provide energy, but they are metabolized differently. Carbohydrates and fats are the primary source of energy, while proteins are mainly used for building and repairing tissues. Maintaining a balanced intake of these macronutrients is important for overall health and well-being. Other dietary components including micronutrients, fiber and polyphenols also play an important role in healthy metabolism. Let’s discuss each of these factors and the three macronutrients in more detail

Carbohydrates

Carbohydrates are a primary source of energy for our bodies and can be classified into two main categories: simple and complex carbohydrates.

Simple carbohydrates are made up of one or two sugar molecules and are found in foods like fruit, milk, and processed foods with added sugars. They are broken down and absorbed quickly and cause a rapid increase in blood sugar levels. Examples include:

Glucose: A simple sugar that is the main source of energy for our cells. It is found naturally in some foods and is also the end product of the digestion of sucrose and complex carbohydrates.
Sucrose: Also known as table sugar, sucrose is a simple carbohydrate made up of one glucose molecule and one fructose molecule. It is found naturally in fruits and vegetables and is often added to processed foods.
Fructose: A simple sugar found naturally in fruits and honey. It is also used as a sweetener in processed foods and beverages.
High fructose corn syrup: A sweetener made from corn starch that is often used in processed foods and beverages. It contains a higher proportion of fructose compared to glucose.

Complex carbohydrates are made up of many sugar molecules linked together in long chains. They can be divided into low glycemic and high glycemic types. Low glycemic complex carbohydrates are slowly broken down and absorbed by the body, leading to a gradual increase in glucose. They are found in foods like whole grains, legumes, and vegetables.** High glycemic** complex carbohydrates are more quickly broken down and can cause a faster rise in blood glucose. Examples of high glycemic complex carbohydrates include bread, pasta, white rice, and potatoes. The relative increase in blood sugar levels from specific complex carbohydrates can vary between individuals, but the glycemic index gives a general idea of how rapidly the carbohydrate is digested and absorbed by an average person. Table 1 lists the carbohydrate content, calories and average glycemic index of several simple and complex carbohydrates.

Table 1

Food	Carbohydrate (g/100g)	Calories / 100g	Glycemic index
Glucose	100	380	100
Sucrose	100	387	65
HFCS	76	281	62
Corn Meal	79	370	68
White Flour	76	364	85
Wheat Flour	73	339	65
Bread (white)	49	265	75
Bread (whole wheat)	41	247	74
Rice (white, cooked)	28	130	73
Rice (brown, cooked)	23	111	68
Pasta (white)	25	131	50
Pasta (whole wheat)	27	124	37
Potato (white, cooked)	20	87	72
Sweet Potato (cooked)	20	86	44
Barley (cooked)	28	122	28
Quinoa (cooked)	21	120	53
Bulgur (cooked)	19	83	48
Oats (whole, cooked)	12	71	55
Lentils (cooked)	20	165	28
Chickpeas (cooked)	30	180	28
Kidney Beans (cooked)	23	127	24
Black Beans (cooked)	24	132	30

The way our body metabolizes the different types of carbohydrates has specific effects on our metabolism and health. When we consume simple carbohydrates, especially those with added sugars, glucose levels rise quickly. Over time, this can lead to insulin resistance, which is a risk factor for type 2 diabetes. Consuming too many simple carbohydrates, especially added sugars can contribute to obesity and poor metabolic health.

Complex carbohydrates, especially low glycemic types, cause a slower rise in blood glucose, and are generally considered healthier choices. They provide longer-lasting energy and are often rich in fiber, vitamins, and minerals. Fiber helps slow down the absorption of sugar into the bloodstream, which can help regulate blood sugar levels and keep us feeling full for longer.

In summary, carbohydrates are an important part of our diet, but it’s important to choose the right types. Opting for complex carbohydrates, particularly low glycemic options like whole grains, legumes, and vegetables, can provide lasting energy and important nutrients. Limiting simple carbohydrates, especially those with added sugars, can support overall health and reduce the risk of chronic diseases.

Fats

Dietary fats are essential for many body functions, including energy storage, hormone production, and cell membrane structure. Let’s explore the different types of dietary fats and their effects on metabolism and health.

Saturated fats are typically solid at room temperature and are found primarily in animal products like meat, dairy, and some tropical oils like coconut oil. Saturated fats have been linked to increased levels of LDL cholesterol, which can contribute to a higher risk of heart disease.

Unsaturated fats are liquid at room temperature and are found in plant-based foods and oils, such as olive oil, avocados, and nuts. Unsaturated fats are generally considered healthier than saturated fats. Monounsaturated fats are a type of unsaturated fat found in foods like olive oil, avocados, and nuts. They have been shown to help lower LDL cholesterol levels and increase HDL cholesterol levels, which can reduce the risk of heart disease.

Omega-3 and omega-6 fatty acids are two types of polyunsaturated fats found in the diet. Omega-3 fatty acids are found in foods like fatty fish (salmon and sardines), flaxseeds, and chia seeds. They have anti-inflammatory properties and have been linked to a reduced risk of cardiovascular disease and some types of cancer. Omega-6 fatty acids are found in vegetable oils, nuts, and seeds. While they can be a useful energy source, consuming too much omega-6 relative to omega-3 may increase inflammation.

The way our body metabolizes different types of fats can have different effects on our health. When we consume excessive amounts of saturated fats, our liver increases the production of LDL cholesterol, which can contribute to the development of heart disease. On the other hand, consuming unsaturated fats, especially monounsaturated and omega-3 fatty acids, can help improve cholesterol levels and reduce inflammation. While some fats may be healthier than others, all fats have a higher caloric density. Consuming too much of any type of fat can lead to an energy surplus, weight gain and obesity. Limiting saturated fats and maintaining a balanced intake of omega-3 and monounsaturated fats can contribute to overall metabolic health.

Protein

Dietary protein is a crucial macronutrient with many important roles in the body. It is essential for the growth, repair, and maintenance of tissues, production of enzymes, hormones, and other molecules. Let’s explore the details of protein composition, absorption, metabolism, and its role in muscle protein synthesis.

Proteins are made up of smaller units called amino acids. There are 20 different amino acids that the body uses to build proteins. Of these, 9 are essential amino acids This means that the body cannot produce them and they must be obtained through the diet. The other 11 are non-essential amino acids, which the body can make from other molecules. Despite the names, all of the amino acids perform important functions in the body and are essential to health.

When we consume protein, our digestive system breaks it down into individual amino acids. These amino acids are absorbed into the bloodstream and transported to the tissues. The body can use these amino acids to build new proteins, such as muscle tissue, or to replace proteins that have been damaged or broken down.

The process of building new proteins is called protein synthesis. This is particularly important for muscle, as physical activity causes small areas of damage to muscle fibers, which need to be repaired and rebuilt. Consuming adequate amounts of protein containing essential amino acids is crucial for muscle protein synthesis, maintenance of lean body mass, strength and a healthy metabolism.

The quality and digestibility of protein can vary depending on the source. Animal-based proteins, such as meat, poultry, fish, eggs, and dairy products, are considered “complete” proteins because they contain all 9 essential amino acids in adequate amounts. Plant-based proteins are often considered “incomplete” because they may be low in one or more essential amino acids. It is possible to get an adequate amount of all essential amino acids by consuming a large amount and a variety of plant-based proteins in combination with complex carbohydrates (e.g. rice-pea blend) and fiber.

Some examples of high-quality protein sources include:

Animal-based: lean meats, poultry, fish, eggs, and low-fat dairy products
Plant-based: soy products (tofu, edamame), legumes (beans, lentils, peas), nuts, and seeds

The recommended daily intake of protein varies depending on factors such as age, sex, and physical activity level. The minimum guideline is to consume at least 0.8 grams of protein per kilogram (0.4 grams per pound) of ideal body weight per day to prevent deficiency. Recent research suggests that protein consumption of at least 1.5-2.2 grams per kilogram (0.7-1 gram per pound) of ideal body weight per day is optimal, especially for people who are recovering from illness, doing resistance exercise and / or over 50. **Tables 2 and 3 **provide the protein content for common animal and plant sources of protein as well as the fat and caloric content of these foods to help guide choices.

In summary, dietary protein plays key roles in the growth, repair, and maintenance of tissues, as well as the production of important signaling molecules in the body. Consuming an adequate amount of high-quality protein sources that provide all essential amino acids is critical for muscle protein synthesis and metabolic health.

Micronutrients

Micronutrients are components in our diet that are required for metabolism but do not serve as fuel sources or structural components of cells. The term micronutrient indicates that they are required in small amounts relative to macronutrients. Most micronutrients are vitamins or minerals. Minerals are inorganic molecules that are required for cellular function. Examples include sodium, potassium, chloride, calcium, magnesium, phosphorus, iron and zinc. When dissolved in water, minerals can also be called electrolytes.

Vitamins are molecules that are involved in important aspects of metabolism. Examples include vitamin A (Beta carotene), vitamin C (ascorbic acid), vitamin D (1-25 hydroxycholecalciferol), and several different B vitamins. Some of these vitamins can be made in the body, but most need to be provided through the diet. If there is not enough of a particular vitamin in the diet, a deficiency may develop that impairs metabolic processes. Some vitamins need to be modified in the body to be effective. Deficiencies can result from variations or changes in the metabolic pathways that activate the vitamin. Vitamins and minerals are involved in many metabolic functions including blood pressure control, electrolyte balance, brain and nerve function, cell growth, tissue repair, wound healing, blood cell production and immune system function.

Micronutrients and Cancer

The relationship between micronutrients and cancer is complex, as micronutrients can play both protective and potentially harmful roles in cancer development and progression. Let’s explore how some key micronutrients are related to cancer.

Antioxidants (Vitamin C, Vitamin E, and Selenium):

Antioxidants help protect cells from damage caused by harmful molecules called free radicals. This damage, known as oxidative stress, contributes to the development of cancer. Studies have shown that foods that are rich in antioxidants such as fruits and vegetables are associated with a lower risk of certain types of cancer. However, high-dose antioxidant supplements have not been proven to prevent cancer and may even be harmful in some cases.
Vitamin D:

Vitamin D is produced in the skin upon exposure to sunlight and found in some foods including fatty fish, meat, eggs, mushrooms and dairy products. Vitamin D has been linked to a reduced risk of several types of cancer, including colorectal, breast, and prostate cancer. Vitamin D helps regulate cell growth, immune function and may have anti-inflammatory effects.
Folate (Vitamin B9):

Folate is important for the synthesis and repair of DNA. Low folate levels are associated with an increased risk of certain cancers, such as colorectal and breast cancer. Some studies suggest that high doses of folic acid (the synthetic form of folate) from supplements may increase the risk of certain cancers, particularly in people with pre-existing precancerous lesions.
Iron:

Iron is essential for the formation of red blood cells and the transport of oxygen throughout the body. However, excessive iron levels have been linked to an increased risk of some cancers, particularly colorectal cancer. This may be because iron can contribute to the formation of free radicals and cause oxidative stress.
Calcium:

Calcium is important for bone health and may play a role in cancer prevention, particularly in the colon. Some studies have shown that higher calcium intake may be associated with a reduced risk of colorectal cancer. However, the relationship between calcium intake and other types of cancer is less clear, and more research is needed.

It’s important to note that the relationships between micronutrients and cancer are complex and can be influenced by various factors, such as the dose, form, and timing of micronutrient intake, as well as individual genetic variations and overall dietary patterns. While a diet rich in fruits, vegetables, and whole grains can provide a wide range of essential micronutrients and may help reduce cancer risk, the use of high-dose micronutrient supplements has not been shown to reduce cancer risk and may be harmful in some cases.

In summary, micronutrients play important roles in maintaining overall health, and some, like antioxidants and vitamin D, may have protective effects against certain types of cancer. However, the relationships between micronutrients and cancer are complex, and more research is needed to fully understand their roles in cancer prevention and progression. Consuming a balanced diet with a variety of nutrient-dense foods is generally the best approach to ensure adequate micronutrient intake and support overall health.

Fiber and the gut microbiome

Dietary fiber is a type of carbohydrate that is not digested by the body but plays a crucial role in maintaining good health. It is so important that it could be considered to be the “fourth macronutrient”. It is found in plant-based foods such as fruits, vegetables, whole grains, and legumes. Fiber is important for many aspects of health, including digestive function, weight management, glucose control, and cardiovascular health. Dietary fiber can be divided into soluble and insoluble forms based upon its ability to dissolve in water. Soluble and insoluble fiber are both important for maintaining a healthy gut microbiome, but they have distinct characteristics and play different roles in the digestive system.

Soluble Fiber:

Soluble fiber dissolves in water, forming a gel-like substance in the digestive tract. It is found in foods such as oats, barley, legumes, fruits (like apples and citrus), and vegetables (like carrots and peas). Soluble fiber is readily fermented by the beneficial bacteria in the colon, producing short-chain fatty acids (SCFAs) such as butyrate, propionate, and acetate. It acts as a prebiotic, selectively stimulating the growth and activity of beneficial gut bacteria. The SCFAs produced from soluble fiber fermentation help maintain the health of the gut lining, reduce inflammation, and improve nutrient absorption. Soluble fiber can help regulate blood glucose through the effects of SCFAs on the gut and improves cholesterol levels by binding to bile acids.

Insoluble fiber does not dissolve in water and remains largely intact as it passes through the digestive system. It is found in foods such as whole grains, wheat bran, nuts, seeds, and the skins of fruits and vegetables. Insoluble fiber is less readily fermented by gut bacteria compared to soluble fiber, but it adds bulk to the stool, promoting regular bowel movements and preventing constipation. Insoluble fiber helps maintain the pH balance in the colon, preventing the growth of harmful bacteria and reducing the risk of colon cancer. Insoluble fiber speeds up the transit of food through the colon, reducing the exposure of the gut lining to toxins and carcinogens.

Both soluble and insoluble fibers are essential for maintaining a diverse and balanced gut microbiome. The fermentation of soluble fiber produces SCFAs that feed the beneficial bacteria, while insoluble fiber promotes the growth of a diverse microbial community by providing a matrix for bacteria to adhere to and colonize. A diet rich in both types of fiber helps maintain the integrity of the gut lining, reduces inflammation, and supports the growth of beneficial bacteria. This balance is crucial for overall gut health, immune function, and metabolic regulation.

It’s important to consume a variety of fiber-rich foods to ensure an adequate intake of both soluble and insoluble fiber. The recommended total dietary fiber intake is 25-38 grams per day, depending on age and sex. Gradually increasing fiber intake, staying hydrated, and engaging in physical activity can promote optimal gut health and maintain a balanced microbiome.** Tables 4 and 5** show the total, soluble and insoluble fiber content of common vegetables, fruits, grains and nuts.

Polyphenols

Polyphenols are a family of naturally occurring compounds found in plants. These compounds have antioxidant properties and play a significant role in plant defense mechanisms against ultraviolet radiation, pathogens, and other environmental stresses. Polyphenols are abundant in a variety of foods. Flavonoids, such as quercetin and catechins, are found in apples, onions, tea, and cocoa. Phenolic acids, like chlorogenic acid and caffeic acid, are present in coffee, artichokes, and certain fruits. Stilbenes, including resveratrol, are found in grapes and red wine. Lignans are found in flaxseeds, sesame seeds, and whole grains.

Polyphenols have a wide range of health benefits due to their antioxidant, anti-inflammatory, and other bioactive properties. They can neutralize free radicals, which reduces oxidative stress and cellular damage. Polyphenol intake is associated with a lower risk of chronic diseases such as cardiovascular diseases, diabetes, and neurodegenerative disorders. Polyphenols can improve the function of endothelial cells that line blood vessels, reduce blood pressure, and enhance insulin sensitivity. Many promote the growth of beneficial gut bacteria, supporting gut health.

Polyphenols have been studied for their potential anticancer properties. Epidemiological evidence suggests that diets rich in polyphenols are associated with a lower risk of certain cancers. The anticancer effects of polyphenols are attributed to several mechanisms, including their antioxidant and anti-inflammatory properties, as well as their ability to modulate the molecular changes that lead to cancer.

Dietary strategies

The combination of nutrients included in the diet can be referred to as a dietary plan or strategy. Let’s explore the different dietary strategies based on their macronutrient composition and how they differ from one another.

Omnivore diet: An omnivore diet includes both plant and animal-based foods. The macronutrient composition can vary depending on the specific foods chosen, but generally, an omnivore diet includes a balance of carbohydrates, fats and protein.
- Mediterranean diet: This is a type of omnivore diet that emphasizes plant-based foods, such as vegetables, fruit, whole grains, legumes, and nuts. It also includes moderate amounts of fish, poultry, eggs, and dairy, with limited red meat consumption. Olive oil and avocados are the primary source of fat. This diet is rich in fiber, healthy fats, and antioxidants.
- Standard American diet (SAD): This type of omnivore diet is characterized by a high intake of processed foods, added sugars, red meat, saturated fats and seed oils. It tends to be low in fruits, vegetables, and whole grains. The SAD is high in calories and low in essential nutrients and fiber, which can contribute to obesity, metabolic dysfunction and chronic diseases.
Carnivore diet: A carnivore diet consists solely of animal products, such as meat, fish, eggs, and dairy. It excludes plant-based foods, including fruits, vegetables, grains, and legumes. This diet is high in protein and fat, particularly saturated fat, and very low in carbohydrate and fiber.
Ketogenic diet: A ketogenic diet is a high-fat, moderate protein and fiber, and very low-carbohydrate diet. The goal is to induce a metabolic state called ketosis, where the body primarily burns fat for fuel instead of carbohydrates. Typically, carbohydrate intake is limited to less than 50 grams per day, with over 80% of calories coming from fat sources.
Vegan diet: A vegan diet excludes all animal products, including meat, fish, eggs, dairy, and honey. It relies solely on plant-based foods, such as fruits, vegetables, whole grains, legumes, nuts, and seeds. The macronutrient composition can vary depending on food choices, but typically includes a higher proportion of carbohydrates and fiber and lower amounts of protein and fat compared to omnivore diets. Vegans need to pay close attention to ensuring that they get enough essential nutrients, such as protein, vitamin B12, iron, calcium, and omega-3 fatty acids, which are more readily available in animal-based foods.

In summary, these dietary strategies differ in their macronutrient composition and sources. Each diet has advantages and disadvantages, so it’s essential to consider individual nutritional needs and health goals when choosing a dietary plan. The Standard American Diet does not have any health benefits and should be avoided by anyone seeking to reduce their cancer risk. Carnivore and ketogenic diets may work well for some people, but they are difficult to adhere to and have major limitations due to high fat and lower fiber and protein intake. Vegan and Mediterranean style omnivore diets provide the best balance of healthy nutrient intake including low saturated fats, high fiber, polyphenols, and adequate protein intake. A vegan diet may be difficult for many to adhere to, and achieving an adequate amount of quality protein intake can be a challenge. For those reasons, a mediterranean style omnivore diet is likely to be the most practical option for most people.

Summary of Practical Nutritional Strategies to Minimize Cancer Risk

Focus on whole foods; limit or eliminate processed foods. The SAD is BAD.
Make the majority of your diet plant based (70-80% vegetables, fruit, nuts)
Carbohydrates: Limit or eliminate simple carbohydrates (glucose, sucrose (sugar), fructose, high fructose corn syrup). Include complex carbohydrates in moderation; prioritize low glycemic carbohydrates.
Fats: Low to moderate fat intake**. Limit saturated fats. Focus on unsaturated and monounsaturated fats (olive oil, avocados, tree nuts, fatty fish).
Protein: Prioritize protein intake goals: 1.5-2.0 g/kg IBW/day (0.7-1 g/pound IBW/day). 3 meals, 30-50 g/meal + 1 snack. If you include animal protein, focus on wild caught salmon, other fatty fish, free range poultry, lean grass fed beef, and wild game. High protein greek yogurt, eggs and tree nuts are also excellent healthy protein sources.
Fiber: Focus on fiber intake goals: 25-40 grams per day. Fresh, preferably organic vegetables; 10 or more different types per week, mostly green and leafy, raw or lightly cooked.
Polyphenols:** Brightly colored vegetables and fruits** usually have a high content of polyphenols. Examples include tomatoes, red and yellow peppers, purple cabbage and berries. Try to include several of these in your diet every day. Coffee, cocoa or dark chocolate, green tea and spices such as turmeric are also great sources of polyphenols.
Perfection is not necessary. There will be times when it is practically difficult to adhere to a healthy diet plan. Don’t worry! Modest (80-90%) compliance will lead to significant improvement in your metabolic health and cancer risk.

Factors that increase the chance of success of nutritional changes and weight loss

Work with a partner or coach.
Measure and track results (food journal, app, CGM).
Make sequential changes starting with the area of greatest impact.
Optimize other areas of health (exercise, Sleep, stress and psychosocial health)
Structure your life to encourage healthy habits (Remove unhealthy food from the pantry, take healthy lunches to work, TRF to limit snacking)

Additional Nutritional Resources:

Tables 1-5 listing the carbohydrate content, calories and glycemic index, protein and fiber content of common foods are included at the end of this section.

Meal Timing

The timing of meals and the intervals between them can have significant effects on metabolic health. Two key concepts in this area are prolonged fasting and time-restricted feeding. Let’s explore these concepts and their impact on metabolism.

Prolonged Fasting

Prolonged fasting refers to the practice of going without food for an extended period, typically 24 hours to several days. Prolonged fasting induces many metabolic changes which are driven by the body’s need to adapt to the absence of nutrient intake and to maintain energy homeostasis.

During the initial stages of fasting, the body depletes its glycogen stores and shifts its energy source from glucose to fat. This involves the breakdown of triglycerides in adipose tissue into free fatty acids and glycerol, which are used for energy production. The liver converts the fatty acids into ketone bodies which serve as an alternative energy source. As fasting continues, gluconeogenesis becomes the primary pathway for maintaining blood glucose. This Involves the synthesis of glucose from non carbohydrate sources such as lactate, glycerol, and some amino acids. These metabolic adaptations result from hormonal changes including increased glucagon and growth hormone, reduced insulin and thyroid hormones. Prolonged fasting also stimulates autophagy, the breakdown and recycling of damaged cellular components. Autophagy may have a role in decreasing the risk of some chronic conditions, including cancer, but the evidence supporting this is limited.

Prolonged fasting can also have many potential drawbacks, including increased stress hormone levels, decreased muscle mass, and nutrient deficiencies. These factors suggest that risks of prolonged fasting may outweigh the benefits for most patients with, or at risk of cancer.

Time Restricted Feeding

Time-restricted feeding (TRF) is a form of intermittent fasting that involves limiting food intake to a specific window of time each day, typically ranging from 6 to 12 hours. This approach aims to align food intake with the body’s natural circadian rhythms and to reduce the amount of time that calories are consumed. This can have several benefits for metabolic health:

TRF reduces energy intake in most cases. This occurs by compressing the number of meals and / or the time that food is consumed, which reduces the calories consumed. It may also be helpful by restricting breakfast and/or late night snacks, which often include calorie dense processed foods, simple carbohydrates and saturated fats. Eating within a consistent time window can help match nutrient intake to the body’s internal clock, or circadian rhythm. This is important for metabolic function and sleep quality. TRF may also improve insulin sensitivity, reduce inflammation and increase fat burning, particularly during the fasting period.

The effects of TRF can depend on several factors, such as the length of the feeding window, the timing of meals within that window, and the overall quality of the diet. More research is needed to fully understand the long-term effects of TRF on metabolic health and cancer risk.

In summary, the timing of meals and the intervals between them can have significant impacts on metabolic health. Prolonged fasting and time-restricted feeding have gained attention for their potential benefits, such as improved insulin sensitivity, increased fat burning, and reduced inflammation. These approaches are not suitable for everyone, and it’s important to consider individual health status and consult with a healthcare professional before making significant changes to meal timing or fasting routines. Ultimately, a balanced diet combined with consistent meal timing that aligns with the body’s natural circadian rhythms may be the most sustainable approach for promoting long-term metabolic health.

Weight Loss

Achieving weight loss while preserving lean mass and maintaining overall metabolic health requires a combination of dietary strategies, physical activity, and lifestyle modifications. Here are some of the most effective approaches:

Balanced calorie reduction:

Gradually reducing calorie intake while maintaining a balanced macronutrient distribution can promote steady weight loss without compromising lean mass. A modest calorie deficit of 500-750 calories per day can lead to a sustainable weight loss of 1-2 pounds per week. It’s essential to ensure that the diet still provides adequate protein, healthy fats, and complex carbohydrates to support overall health and maintain muscle mass.
High-protein diet:

Consuming a higher proportion of calories from protein can help preserve lean mass during weight loss. Protein has a higher thermic effect of food (TEF), meaning it requires more energy to digest and metabolize, and it helps maintain satiety. Aim to consume at least 1.5 grams of protein per kilogram of ideal body weight, sourced from high-quality, lean protein sources such as poultry, fish, legumes, and low-fat dairy products.
Resistance training:

Engaging in regular resistance training (weightlifting or bodyweight resistance exercises) is crucial for maintaining lean muscle mass during weight loss. Aim to perform strength training exercises 2-3 times per week, targeting all major muscle groups. Maintaining muscle mass not only helps preserve metabolic health but also promotes a higher resting metabolic rate, aiding in long-term weight management.
High-intensity interval training (HIIT):

Incorporating HIIT into your exercise routine can help maximize fat loss while preserving lean mass. HIIT involves alternating short bursts of high-intensity exercise with periods of rest or low-intensity activity. This type of training has been shown to improve insulin sensitivity, boost fat burning, and promote cardiovascular health. Aim to perform HIIT sessions 1-2 times per week, in addition to resistance training and moderate-intensity cardio.
Adequate sleep and stress management:

Getting enough quality sleep and managing stress levels are often overlooked but critical aspects of weight loss and metabolic health. Poor sleep and chronic stress can disrupt hormonal balance, leading to increased appetite, cravings, and insulin resistance. Aim for 7-9 hours of quality sleep per night and practice stress-reducing techniques such as meditation, deep breathing, or yoga.
Nutrient-dense, whole-food diet:

Focusing on nutrient-dense whole foods can help ensure that your diet provides essential vitamins, minerals, and fiber while minimizing excess calories from added sugars and unhealthy fats. Prioritize fruits, vegetables, whole grains, lean proteins, and healthy fats like olive oil, nuts, and avocados. Limit processed snacks, sugary beverages, and high-fat, high-sugar treats.
Consistent monitoring and adjustment:

Regularly monitoring progress through body weight and body composition measurements and performance metrics can help ensure that your weight loss plan is effective and allows for timely adjustments if needed. If progress stalls or lean mass starts to decline, consider reassessing calorie intake, macronutrient distribution, and training intensity to optimize results.

Sustainable weight loss and improved metabolic health takes time and requires consistency. It’s essential to adopt a long-term strategy and make gradual changes that build upon one another and can be maintained. Consulting with a registered dietitian or certified fitness professional can provide personalized guidance and support throughout your weight loss journey.

The bottom line is that you will need to be in a significant energy deficit to lose weight. You can achieve this in several ways: Caloric restriction (reducing the amount of calories you take in), dietary restriction (changing your dietary strategy to avoid certain foods, thereby reducing calorie intake) and exercise (which increases energy expenditure). There are several tools for caloric restriction: Fasting, time restriction, macronutrient restriction, reduction in portion size and medications.

General strategy for weight loss

-Determine baseline body composition and personal preferences.

-Tailor your nutritional and exercise strategies to match these.

-Sustainable results are achieved with sequential changes and a focus on overall health.

-The most practical effective order of nutritional changes for most people is:

Change what you eat.

Eliminate or minimize processed foods; focus on whole foods.

Minimize or eliminate simple carbohydrates

Minimize high glycemic complex carbohydrates

Minimize saturated fats and fried foods

Focus on protein intake; 1.5 g/kg/day; 2+ g/kg/day if vegan or resistance training
Change how much you eat.

Reduce portion size

Eliminate one meal: Must maintain protein intake.
Change when you eat.

Time restriction: Primarily reduces caloric intake; limits calorically dense foods.

Prolonged periodic fasting: > 24 hours water and electrolytes only.

May be helpful to “jump start” weight loss for some people.

-Synergistic changes: Add exercise, optimize sleep, add heat and cold exposure.

-Pharmacological tools: GLP-1 agonists can be considered as a tool to “jump start” weight loss in combination with lifestyle interventions.

-Most effective to make changes with a partner or support team.

-Long term goal is permanent lifestyle changes.

Specific Nutritional Strategies for Cancer Patients:

-Determine Baseline Body Composition, Energy Balance and Nutrition

-Optimize Energy Balance

-Optimize Macronutrient Strategy

-Supplements to Address Deficiencies

-Strategy must be individualized based upon disease phase:

Prevention:

Comprehensive health optimization:

Weight loss, nutritional optimization.

Survivorship:

Comprehensive health optimization: