How to Customize Your Diet



Diets suck, which is probably why I’ve never written a diet book and also why I think most diet books are silly marketing ploys. Why?

Simple: most diets involve a “one-size-fits-all” approach that paints an entire population with a broad nutritional brush, without taking into consideration genetic individuality, personal health history, nutrient, vitamin and minerals holes that need to be addressed, etc.

Take the currently popular “ketogenic” diet for example. This very high-fat, very low-carb diet is championed by enthusiasts as the perfect way to lose weight, enhance cognition, increase endurance and beyond. And it does indeed work for these goals (for enhanced endurance, I personally followed a strict ketogenic diet for years while racing Ironman triathlon, and occasionally use ketosis as a brain-boosting strategy on mentally difficult days).

But when reviewing the bloodwork and biomarkers on the lab tests of my clients and people for which I do health and nutrition consults – notably people who are following one of these ketogenic diets – I’ve witnessed concerningly high levels of LDL cholesterol (skyrocketing over 400), along with high triglycerides (which can be a risk factor for heart disease and serious liver issues) and high inflammation. How could this be?

Basically, there is a condition called “familial hypercholesteremia” (HeFH) – that affects up to 10% of people worldwide. People with this condition tend to experience a metabolic firestorm in response to a high-fat diet because their cholesterol and inflammatory markers increase dramatically in response to foods such as coconut oil, butter, fatty fish and meats, eggs, etc.

As my friend and former podcast guest Chris Masterjohn has written and podcasted about himself here, the best way to get to the root of the problem in HeFH is to take the one gene for the LDL receptor responsible for contributing to this condition and try to bring it up to the expression level that would be found in someone without HeFH. How is this done? From a scientific standpoint, it can be accomplished by maximizing the biological activity of thyroid hormone and by maximally suppressing the activity of a gene called PCSK9, which is done by increasing insulin signaling. In brief, from a dietary management standpoint (and much to the chagrin of ketogenic zealots), this all comes down to eating a low-fat, fiber-rich, high-carbohydrate diet and replacing saturated fat with polyunsaturated fat – using a diet very similar to an ancestral Kitavan islander diet rich in fiber-dense carbohydrate such as coconut meat, starchy tubers, and fresh fruit.

Another example of the same dietary advice not being be good for everyone (and one big reason why, despite the prevalence of diet books, we have failed so miserably at controlling the obesity epidemic), is the wild variation in blood sugar response that can occur when subjects in controlled dietary studies eat foods like cookies, bananas, sushi and whole-grain bread. The latest research on this newly observed phenomenon suggests that each person’s capacity to extract energy from foods differs dramatically because the interactions among one’s genes, microbiome, diet, environment and lifestyle are so infinitely complex, and also suggests that common measurements of the sugar content of foods, such as the glycemic index, may be relatively useless when compared to looking at individualized blood sugar responses to foods.

One recent six-month study, funded by the European Union and called Food4Me investigated 1,500 participants in seven European countries who were randomly given personalized dietary advice based on their genetic data, or instead told to follow standard dietary prescriptions like such as eating lots of fruits and vegetables, lean meats and whole grains. Those who were in the personalized diet cohort fared far better than those in the one-size-fits-all diet group, making the researchers pretty confident that personalized diets are the way forward.

Coffee is another perfect example of the need for diet individuality.  Current guidelines advise no more than four or five cups of coffee per day. And sure, this is fine for roughly half the population that are genetically “fast caffeine metabolizers”, but for the other half who have a variant of a gene called CYP1A2, any more than two cups per day increases the risk of a heart attack and hypertension.

Scientists are slowly beginning to tease out all these connections, and have now linked at least 38 different genes to nutrient metabolism. Variants of these genes are thought to hinder or help absorption or the efficient use of nutrients in foods, which means that depending on your genetic makeup, microbiota, health history and environment, you should consume more or less folate, choline, vitamin C, fatty acids, starches and caffeine.  A host of other such genes exist, including MTHFR (folate, vitamin B metabolism), FTO (body weight and fat composition), TCF7L2 (blood sugar regulation), APOE ε4 (cholesterol) and FADS1 (fatty acid metabolism).

As is obvious, from the failures of a high-fat diet, to individual blood sugar responses to carbohydrates, to genetic variations in the need for major vitamins, minerals and nutrients, the need for dietary customization is enormous. In my opinion, one of the best ways to cut through this confusion is to test your body so that you can truly customize your diet. These tests include:

-Blood testing: a blood test can determine “holes” in the diet that need to be filled from a supplement or food standpoint, such as low vitamin D status (vitamin D can be quite toxic if you’re simply taking it because you heard you should when in fact, your levels are actually already adequate), blood sugar response to certain foods or high blood sugar in general, mineral status, thyroid status, cholesterol status, red blood cell and white blood cell levels, vitamin B, acidity, alkalinity and beyond. Some blood tests can even be used to determine food allergies and intolerances, although most of these are notoriously inaccurate, and which simply give you an exhausting “false positive” list of foods you shouldn’t eat.

-Stool testing: your blood can’t necessarily tell you what’s going on in your gut, but a stool panel allows you to determine presence or absence of certain types of bacteria, yeast, fungus, parasites and digestive inflammation, all of which can then be used to determine the need for certain probiotics, cleansing compounds, the need or non-need to avoid fermentable substances such as simple sugars and starches, etc.

-DNA testing: as one of the most useful and important ways to customize your diet, genetic DNA testing (performed via a simple and inexpensive salivary measurement) is an excellent method to determine not only what your ancestors traditionally ate, but which genes are present or absent that contribute to everything from antioxidant need to blood sugar response to lactate and gluten sensitivities and much more.

When thinking about how to personalize the diet, you should also take into consideration special populations who need to customize their diet based on age, religious or ethical preferences, sporting demands and beyond including:

  • Carbohydrate needs and ketosis appropriateness for aerobic vs. anaerobic athletes and exercisers, how one can restrict excess sugar and starches while still maintaining adequate glycogen levels for explosive or intense activities, and nutrients that tend to be missing from a low-carbohydrate, high-fat diet, a diet an enormous number of people are following.
  • Notoriously missing variables and nutrients that plague a vegan or vegetarian diet, such as creatine, vitamin B12, DHA, taurine and amino acids, and exactly how to fill in these missing gaps.
  • Finally, you should realize the fact that a diet will fluctuate and change as one’s body and one’s gut transforms.
  • How the metabolism of both seniors and kids/adolescents are far different than the general population, and how to support individual dietary needs in both old age and youth.
  • Individual considerations for females vs. males, and how women can support their unique needs, especially to support normal fertility and menstruation.
  • No consideration of food would be complete without a consideration of how the environment has been treated in the harvesting and preparation of the food, and so you should also take into account what is called “conscious consumerism,” including:
  • Find a minimal effective dose of animal products. Optimal intake for the environment is likely around 10% (or less) of total daily calories from animal products, and one should aim to get animal products from farms implementing sustainable crop-livestock integration systems.
  • Aim for moderating amounts of tree nuts and eggs as they can pack more of a deleterious environmental punch (especially when they aren‘t organically grown tree nuts and pasture-raised eggs).
  • Minimize wasted food by using leftovers, planning meals, composting food scraps, giving food scraps to livestock/pets, and buying visually unappealing veggies and fruits.
  • Minimize overeating processed foods (metabolic food waste). Instead prioritize food purchases from farms that incorporate more efficient and sustainable growing methods (e.g., agroforestry, conservation tillage, integrative pest management, water harvesting, drip irrigation, appropriate livestock rotation, etc.). Buying organic and local gives you a better chance of supporting these practices.
  • Eat locally, especially during the peak growing season (and especially if it‘s a food well suited to grow in your region).

Finally, you should realize the fact that a diet will fluctuate and change as one’s body and one’s gut transforms. For example, many individuals who have digestive issues, toxicity or other health complaints need to initially fix their gut or detox with an extremely “clean” and restrictive diet that eliminates notorious problem foods such as dairy, grains, nightshades, red meat, etc. – even the healthy, organic, natural versions of these foods. But once the gut and immune system is healed, these foods can gradually be reintroduced and enjoyed once again!