The Carb-Fat Diet: The Solution to Insulin Resistance

I have been following the research on diets for over thirty years. It is amazing how many diet books are out there. Approximately 4 million new book titles are published annually worldwide. Nonfiction accounts for about 88% of these, or roughly 3.52 million titles yearly. Assuming diet books represent a small but notable fraction of nonfiction—say, 1-2% based on their perennial presence on bestseller lists—this suggests around 35,000 to 70,000 diet books annually. Dividing by 12 months, this yields an estimate of 3,000 to 6,000 new diet books per month globally. That’s a lot! I have not read all of them, by far, but I do sample many of them. One book that is touched-on peripherally in many ways, but not specifically, is the carb-fat diet. I’ll give you an overview of what it entails.

The foundation of the diet is simple: Insulin is the culprit.

All our problems with weight gain are because of insulin. Insulin is the worst thing you can have in your body – except that you can’t live without it. Insulin gets glucose into cells so they can survive. It also helps protein synthesis – meaning creating the structure and function of all your cells. People who don’t make insulin die – either of ketoacidosis, or starvation both of which happen because glucose cannot get in the cells without it.

However, there are many problems associated with too much insulin.

The Dark Side of Insulin Resistance:

Promotion of Fat Storage:

Insulin facilitates glucose uptake into cells and promotes the storage of fat, lipogenesis, and inhibits lipolysis (fat breakdown), leading to increased fat accumulation. This creates a vicious cycle where excess fat storage contributes to weight gain. Then obesity further drives insulin resistance, elevating insulin levels and creating more fat. These are the people who say, “I get fat on water!”

Insulin Resistance:

Excess insulin causes insulin resistance, where cells become less responsive to insulin signals. To compensate, the pancreas produces more insulin which causes more resistance. Insulin resistance blocks glucose from getting into cells, leading to higher blood glucose levels, which are then stored as fat, contributing to obesity.

Disruption of Appetite Regulation:

High insulin levels can interfere with the brain’s appetite regulation centers, particularly by affecting leptin signaling (the hormone that signals satiety), which leads to increased hunger and overeating, further promoting weight gain. Insulin also stimulates reward pathways in the brain, increasing cravings for high-calorie, carbohydrate-rich foods.

Impaired Fat Burning:

Elevated insulin suppresses the activity of hormone-sensitive lipase, an enzyme responsible for breaking down stored fat. This reduces the body’s ability to use fat as an energy source, favoring fat storage over fat burning. We normally use fat to make about 60% of our energy, so this loss is significant.

Increased Visceral Fat Accumulation:

Hyperinsulinemia is particularly associated with the accumulation of visceral fat (fat around internal organs), which is metabolically active and linked to higher risks of obesity-related complications like type 2 diabetes, kidney disease, cardiovascular disease, and metabolic syndrome.

Inflammation:

Excess insulin can contribute to low-grade systemic inflammation, often seen in obesity. This inflammation exacerbates insulin resistance and promotes further fat storage.

Metabolic Dysfunction:

Insulin also disrupts mitochondrial function, reducing energy expenditure and making weight loss more difficult. It actually decreases the production of ATP – the energy of the cell so you have less energy, like running on low batteries.

Hormonal Imbalances:

High insulin levels can disrupt other hormones involved in weight regulation, such as cortisol, growth hormone, and sex hormones (e.g., testosterone and estrogen). These imbalances can contribute to fat gain, particularly in specific areas like the abdomen.

Polycystic Ovary Syndrome (PCOS):

In women, hyperinsulinemia is a key driver of PCOS, a condition often associated with obesity, infertility, and metabolic syndrome. Insulin resistance in PCOS increases androgen production, which promotes abdominal fat accumulation and weight gain.

Energy Partitioning:

Excess insulin shifts energy partitioning toward fat storage rather than muscle growth or energy expenditure. This means that calories consumed are more likely to be stored as fat rather than used for other metabolic processes, giving you less energy.

Muscle Wasting:

Resistance to insulin decreases the ability to make new proteins and increase muscle mass.

Impact on Gut Microbiota:

Emerging research suggests that hyperinsulinemia may alter gut microbiota composition, favoring bacteria that extract more energy from food, contributing to weight gain, as well as bowel issues like IBS.

Potential Behavioral Effects:

Chronically high insulin levels may contribute to fatigue or low energy due to impaired glucose utilization in cells, leading to reduced physical activity and further weight gain. The low energy in the brain contributes to depression, anxiety, and Alzheimer’s Disease. Indeed, some researchers have suggested that dementia be called “Diabetes type 3.”

What is the answer?

The solution to the problem of insulin has been hotly debated for over a century. Some diets deal with the effects of insulin, but most don’t even pay any attention to it. The two primary ways of dealing with insulin resistance through diet are the ketogenic diet and the low-fat vegan diet.

KETO

The “ketogenic diet” has been used for many years as a weight loss diet. It was first introduced in the 1920’s as a treatment for children with epilepsy. The ketones calm the brain and stop seizures. At first, doctors put the children on a fast, which caused them to burn fat and make ketones, stopping the seizures. But you can’t fast forever, so a brilliant pediatrician came up with the idea to “trick the body” into thinking it was fasting by giving only fat to eat. It worked!

Since then, the ketogenic diet has been used for weight loss. One of the more popular ketogenic diets came out of the 1970’s, the Atkins Diet Revolution, which is still popular today. The idea of a ketogenic diet is that when you don’t eat glucose (sugar) you don’t produce insulin, so you keep insulin low. This prevents all the problems with insulin noted above. The body burns mostly fat for energy, so the cells don’t fill up with glycogen (a storage form of glucose) and become resistant to insulin. Essentially, you are training your metabolism to burn fat for energy. The liver can make fat into ketones which can be used by the brain and other organs, so they don’t starve for sugar. Since glucose is a “high-octane” or “hot” fuel, it can cause inflammation, but ketones do not. This is a very effective way to lower glucose, glycogen, and insulin levels. It has a decades-long history of success, but, alas, it is not sustainable. Almost all the studies of this diet show initial weight loss, but long-term failure. One of the many is Shai et al. (2008) and Meta-Analysis:

• A 24-month study by Shai and colleagues found that the Atkins diet led to greater weight loss at 6 months compared to a low-fat diet, but by 24 months, weight loss was not significantly different due to lower adherence rates (78% for Atkins vs. 90.4% for low-fat diet). This supports the idea that the restrictive nature of the Atkins diet makes long-term adherence challenging.

Low Fat

As noted in the study above, the other option for lowering insulin is a low-fat diet. This may seem counter-intuitive because you can eat all the glucose, starches and sugar you want, but you just avoid fat. This works because fat causes insulin resistance. For about eight hours after eating fat, you are resistant to insulin. Insulin is made, but if you don’t eat fat, the level of insulin declines rapidly after a meal, preventing insulin resistance.

An important part of the low-fat diet is exercise. Glucose is taken up by muscles during exercise without the need for insulin. Those who exercise regularly can do well on a low-fat diet. However, there is still the same issue as there is with all very restrictive diets – they are not sustainable long-term for most people.

Solving the Mystery:

Thus, we have a quandary – both diets work well in the short-term, but neither is a good long-term solution for most people.

Enter the carb-fat diet. This is a long-term solution for everyone. Since insulin resistance from eating fat only lasts about eight hours, it could work to have separate low-carb days and low-fat days. On a low-carb day, you could eat fat like meat, fish, eggs, cream cheese, yogurt, nuts, and so forth, but on a low-fat day you would eat beans, rice, oatmeal, bread, fruit and so forth. You could have vegetables on both days that aren’t high in either fat or carbs.

What’s really good about this diet is that you can choose any day to decide which to do. If you get up in the morning and feel like oatmeal, it could be a low-fat day. If you feel like bacon and eggs, it could be a low-carb day. You could do as many days in a row of either diet, even changing on a monthly basis – or longer!  There is no limit on either side. If you are doing a month of low-fat, but you want to go out with the guys for a steak, then make it a low-carb day and have steak with broccoli, asparagus, or brussels sprouts. The change in diet can be for any day.

The limitation in the diet is to avoid mixing fat and carbs. If you eat fat one day, don’t eat carbs. If you eat carbs, avoid fat. You would especially avoid anything that is a mixture of fat and carbohydrates like ice cream, pastries, candy, French fries, or any fried foods. The idea is to separate carbs and fats so there is no insulin resistance, keeping insulin down. That way we get the best of both diets, and it is sustainable for life. The only foods we don’t eat are those that are high in both fat and carbs.

RULE #1: Do not eat fat and carbs on the same day.

The other great thing about this diet is that you can take advantage of the millions of recipes and websites for both diets. It’s easy to find low-fat recipes for any kind of meal you want. There are millions of websites that will give you ideas on low fat meals. On the other hand, there are millions of recipes and websites that promote a ketogenic, or low-carb, diet.

Rule #2: Do not eat anything that says: “Low-Carb,” “Keto-friendly,” “Low-Fat,” or any suchlike on the label. (Avoid almost everything with a label!)

What can I eat?

I’m glad you asked. You can easily look up the carb and fat content of any food and see what you can eat on what day. The idea is to keep the carbs under 20 grams per day on a low-carb day, and the fat under 20 grams per day on a low-fat day. The following is a summary of what the diet looks like. It is divided into four parts:

• Foods for a Low-Fat day
• Foods for a Low-Carb day
• Foods for either day
• Foods to avoid

Foods for Low-Fat Day

Goal: Low-fat (under 20 grams per day)

• Grains:
  • Brown rice
  • Quinoa
  • Oats
  • Corn
  • Whole wheat/brown rice/lentil pasta with tomato sauce
• Starchy Veggies:
  • Sweet potatoes
  • Mashed/baked potatoes
  • Butternut squash
• Legumes:
  • Lentils
  • Chickpeas/hummus
  • Beans
  • Peas
• Fruits:
  • Apples
  • Berries
  • Pears
  • Oranges
  • Melon
• Proteins (Low-Fat): (each has about 3g of fat per 3 oz)
  • Chicken breast.
  • Turkey breast
  • Cod or tilapia
• Notes: Cook without added fats (e.g., steam, boil).
  

Foods for a Low-Carb Day

Goal: Low-carb (<20g total per day)

• Fats:
  • Olive/Avocado oil
  • Coconut oil
  • Butter
  • Nuts: Almonds, walnuts, macadamias
  • Peanut/almond butter
• Fatty Proteins:
  • Salmon
  • Mackerel or sardines
  • Chicken/pork
  • Beef/Ground beef
  • Eggs
• Dairy:
  • Full-fat Greek yogurt (plain, unsweetened)
  • Cheese
  • Sour cream
  • Cottage Cheese
• Low-Carb Fruit and Veggies:
  • Avocado
  • Olive
  • Coconut (unsweetened)
• Notes: focus on fat as the main calorie source. Cook with oil. Avoid sauces with sugar or starch (salad dressings, ketchup). Avoid breaded meats or vegetables.

Foods for Either Day

These foods have both low carbohydrate and low fat.

Non-Starchy Veggies:

• • Cauliflower/broccoli
  • Green beans
  • Asparagus
  • Bell peppers
  • Cucumber
  • Mushrooms
  • Green salads/sprouts
  • Brussels sprouts
  • (and so forth)
• Lean Proteins:
  • Turkey/chicken breast
  • White fish (haddock, flounder)
  • Tofu
• Flavorings:
  • Herbs (basil, parsley, cilantro).
  • Spices (cumin, paprika, turmeric).
  • Vinegar (balsamic, apple cider, no sugar).
  • Mustard
• Beverages:
  • Water
  • Black coffee (no cream/sugar).
  • Unsweetened tea (green, herbal).

Foods to Never Eat

These foods will stimulate excess insulin and should be avoided.

Processed Carbs:

• • White bread
  • White rice
  • Breakfast cereals
  • Instant mashed potatoes
• Sweet Drinks/Foods:
  • Flavored drinks/soda
  • Fruit juice
  • Candy/chocolate
• High-Fat, High-Carb Combos:
  • Pizza
  • Pasta with oil/sauce/cheese
  • Donuts, pastries, cookies
  • French fries (anything fried)
  • Ice cream
  • Bread/toast with butter
  • Potato with oil/butter/sour cream
  • Burgers/hot dogs with buns
• Non-Food Junk:
  • Margarine
  • Packaged snacks (no matter what the package says)
  • Artificial sweeteners

EXAMPLES: The following comes from GROK AI:

Low-Fat Day Meal Examples

Day 1

Breakfast: Oatmeal with Fruit and Skim Milk (~5g fat)

• 1 cup cooked oatmeal (made with water) – 2g fat
• 1 medium banana, sliced – 0g fat
• 1 cup skim milk – 0g fat
• 1 tsp chia seeds – 3g fat
  Prep: Cook oatmeal, top with banana and chia seeds, serve with skim milk.
  Total: ~300 calories, 5g fat

Lunch: Turkey and Veggie Wrap with Side Salad (~8g fat)

• 1 whole-grain tortilla (8-inch) – 1 slice deli turkey breast (2 oz, low-fat) – 1g fat
• 1 cup mixed greens (lettuce, spinach) – 0g fat
• 1 tbsp hummus – 3g fat
• 1 small apple – 0g fat
• Side salad: 1 cup cucumber, ½ cup cherry tomatoes, balsamic vinegar dressing (no oil) – 0g fat
  Prep: Spread hummus on tortilla, add turkey and greens, roll up. Serve with salad and apple.
  Total: ~350 calories, 8g fat

Daily Fat Total (Breakfast + Lunch): 13g fat
Note: If you eat dinner, have a small plate of brown rice with 3 oz chicken breast and brussels sprouts.

Day 2

Breakfast: Greek Yogurt Parfait with Berries (~6g fat)

• ¾ cup non-fat plain Greek yogurt – 0g fat
• 1 cup mixed berries (strawberries, blueberries) – 0g fat
• ¼ cup low-fat granola – 5g fat
• 1 tsp flaxseeds – 1g fat
  Prep: Layer yogurt, berries, and granola in a bowl, sprinkle with flaxseeds.
  Total: ~250 calories, 6g fat

Lunch: Chickpea Salad with Whole-Grain Bread (~9g fat)

• ¾ cup canned chickpeas (rinsed, drained) – 2g fat
• 1 cup chopped cucumber and red bell pepper – 0g fat
• 1 tbsp light vinaigrette (low-fat) – 3g fat
• 1 slice whole-grain bread – 1g fat
• 1 medium orange – 0g fat
  Prep: Toss chickpeas, vegetables, and vinaigrette. Serve with bread and orange.
  Total: ~400 calories, 9g fat

Daily Fat Total (Breakfast + Lunch): 15g fat
Note: If you eat dinner, have a small green salad with balsamic vinegar, or some steamed cauliflower.

 

Low-Carb Day Meal Examples

Example Day 1

Breakfast: Scrambled Eggs with Avocado

• 2 large eggs (1g carbs)
• 1 tbsp butter (0g carbs)
• ¼ avocado (2g net carbs, 3g total – 1g fiber)
• 1 cup brewed black coffee (0g carbs)
• Total carbs: ~3g net carbs
• Details: Scramble eggs in butter, season with salt and pepper. Slice avocado and serve on the side. Coffee is unsweetened.

Lunch: Cobb Salad (No Dressing Carbs)

• 2 cups romaine lettuce (1g net carbs, 2g total – 1g fiber)
• 3 oz grilled chicken breast (0g carbs)
• 1 hard-boiled egg (0.5g carbs)
• 1 slice bacon, crumbled (0g carbs)
• ¼ cup crumbled blue cheese (1g carbs)
• 2 tbsp olive oil + 1 tbsp red wine vinegar (0g carbs)
• Total carbs: ~2.5g net carbs
• Details: Toss ingredients together. Use olive oil and vinegar as dressing to avoid hidden carbs in pre-made dressings.

Daily Total for Breakfast + Lunch: ~5.5g net carbs

Note: if you eat dinner, have something light, such as a salad, steamed vegetables, or nuts.

Example Day 2

Breakfast: Greek Yogurt with Chia Seeds

• ¾ cup full-fat, unsweetened Greek yogurt (5g carbs)
• 1 tbsp chia seeds (1g net carbs, 6g total – 5g fiber)
• 5 raspberries (1g net carbs)
• Total carbs: ~7g net carbs
• Details: Mix chia seeds into yogurt, top with raspberries. Avoid sweetened yogurt or additional toppings like honey.

Lunch: Tuna Lettuce Wraps

• 4 oz canned tuna in olive oil, drained (0g carbs)
• 1 tbsp mayonnaise (0g carbs)
• 2 large romaine lettuce leaves (0.5g net carbs, 1g total – 0.5g fiber)
• ¼ cucumber, sliced (1g net carbs, 1.5g total – 0.5g fiber)
• 1 oz cheddar cheese, cubed (0.5g carbs)
• Total carbs: ~2g net carbs
• Details: Mix tuna with mayo, season with salt and pepper. Spoon into lettuce leaves, add cucumber slices, and serve cheese cubes on the side.

Daily Total for Breakfast + Lunch: ~9g net carbs

Note: If you eat dinner, have something light like a salad, steamed vegetables, or nuts.

Example Day 3

Breakfast: Bacon and Spinach Omelet

• 2 large eggs (1g carbs)
• 2 slices bacon, cooked (0g carbs)
• ½ cup fresh spinach (0.5g net carbs, 1g total – 0.5g fiber)
• 1 tbsp olive oil (0g carbs)
• Total carbs: ~1.5g net carbs
• Details: Cook bacon, set aside. Sauté spinach in olive oil, add eggs to make an omelet, and crumble bacon inside.

Lunch: Grilled Salmon with Asparagus

• 4 oz grilled salmon (0g carbs)
• 6 asparagus spears (2g net carbs, 3g total – 1g fiber)
• 1 tbsp butter (0g carbs)
• 1 cup arugula (0.5g net carbs, 1g total – 0.5g fiber)
• 1 tbsp lemon juice (1g carbs)
• Total carbs: ~3.5g net carbs
• Details: Grill or bake salmon, season with salt. Sauté asparagus in butter. Serve with arugula drizzled with lemon juice.

Daily Total for Breakfast + Lunch: ~5g net carbs

Note: if you eat dinner, have something light such as a salad, steamed vegetables, or some nuts.

The reason for not mixing carbs and fat on the same day is to prevent insulin resistance. The diseases that we associate with diabetes, such as Alzheimer’s disease, obesity, metabolic syndrome, kidney failure, heart disease, blindness, amputation, and neuropathy are all due to insulin resistance. The problem is not specifically fat, nor is it carbohydrates, the problem is mixing fats with carbohydrates.

It is easy to see how this type of diet is sustainable and healthy. You are not going to have any issues with deficiencies in the diet. There is plenty of room for everything – except junk food! You can satisfy your sweet cravings with fruit on a low-fat day, and have that steak with butter on a low-carb day. Vegetables are available on either day. This could even become a vegan diet for those who don’t eat animal products. It works for those who have insulin resistance already. It works for those who want to lose weight. This could be a long-term solution to diet problems.

 

 

Sources:

[1] https://pmc.ncbi.nlm.nih.gov/articles/PMC7553667/

[2] Epilepsia. 2008 Nov:49 Suppl 8:3-5. doi: 10.1111/j.1528-1167.2008.01821.x.

History of the ketogenic diet; James W Wheless 1

[3] https://www.sciencedirect.com/topics/medicine-and-dentistry/atkins-diet

[4] https://www.mdpi.com/2072-6643/12/12/3774