Personalized Nutrition: Why There Is No One-Size Fits-All Diet Except the Whole Foods Diet

After a gluttonous Christmas in 2013, my husband and I looked at ourselves and decided we had to go on a diet. Things had been spiraling downward for a while. The primary factor was that I had been diagnosed with a chronic condition the year before (fibromyalgia). Pain and fatigue made cooking healthy or moving more just seem too difficult. In my husband’s case, catered meetings and lunches at work meant too many muffins. So we went on a plant-based, nutrient dense diet (advocated by Dr. Fuhrman). I lost weight. My husband did not – even though he swore he only looked at the muffins. What’s with that?

The answer lies in your unique individual makeup. A 2015 study investigated post-meal glucose levels in 800 individuals over the course of a week. They found significant individual variation among the participants in the blood glucose levels caused by different foods, even when they ate the exact same, standardized meals. For example, in one participant sushi caused their blood sugar to rise higher than ice cream, while another found that healthy tomatoes spiked her blood sugar.

Researchers attributed this variability to a combination of physical makeup (weight, blood pressure, etc.), lifestyle and gut microbiome (the unique gut bacteria in our digestive tract). In fact, an algorithm based on these factors was able to accurately predict personalized post-meal glucose reactions to specific foods. Using this information, researchers designed individual nutritional recommendations that eliminated the foods that caused high glycemic reactions, which led to overall lower blood sugar levels among study participants.  It is this individual variability that explains why one of your friends is trying to convince you to eat like a carnivorous caveman (hello, Paleo), while the other swears that her rabbit-food veganism changed her life.

Another example of individual variability in nutrition is sensitivity to cholesterol obtained from the diet. For most of us, the liver produces 85% of our cholesterol and the rest is acquired from our diet. If we eat a cholesterol-rich meal, our body responds by manufacturing less cholesterol to maintain a healthy blood level. However for about 30% of people, when they eat cholesterol high foods, their blood cholesterol goes up. In these cases, the sensitivity to blood cholesterol is blunted, leading to problems regulating healthy levels.

As you might expect, research into the relationship between our individual genetic makeup and nutrition, called nutritional genomics, is a rapidly expanding field. Lactose intolerance is one example of how genes can affect your reaction to food – certain variations of specific genes confer lactose tolerance, while other variations cause intolerance. Many researchers argue that personalized diets are the future of nutrition, rather than broad dietary recommendations or one-size-fits-all diets. However, the application of these research insights are not yet broadly available to enable people to develop an individual diet based on factors like genetics, physical makeup, and gut microbiome.

The good news is that there is one diet plan that is always good for you. What is that diet? Eating whole foods. Not raw, organic, GMO-free or local (although there are lots of good reasons to choose some of those options too). Whole foods mean food as close to their natural state as possible – carrots in the earth, grapes on the vine, or fish in the sea. Real foods are not processed, refined, added to, fortified, or otherwise messed about with by a food chemist. This is the one diet you can’t go wrong following.

More on the benefits of a whole food diet in Part II…


Dr. William Sears. Prime-Time Health (2010):*Version*=1&*entries*=0#

Nutritional Genomics and Lactose Intolerance

Zeevi, D. et al. (2015). Personalized Nutrition by Prediction of Glycemic Reactions.  Cell. 163(5), p. 1079-1094.


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