Perfect Diets? Why They Might Not Exist

Perfect Diets? Why They Might Not Exist

(Last Updated On: April 5, 2019)


Perfect Diets? Why they Might Not Exist

What are the best diets for lowering your risk of disease and for controlling your weight? Low-carbers will tell you it’s one that’s low in carbs while plant-based diet gurus will tell you the secret to health and longevity lies in eating plants.  Then, there are the Paleo followers who eat “primally” and forgo anything that our primal ancestors wouldn’t have eaten. Trying to figure out who’s right is enough to make your head spin. Yet based on recent research, they may all be right and it all comes down to the individual.

The Role Genetics Play in How You Respond to Diets

According to a recent study to be presented at the Allied Genetics Conference, the “best” diet may depend upon your own unique genetics. We’re all dealt a certain genetic hand, the DNA that comes from each of our parents. DNA, in turn, codes for proteins that impact bodily functions. These same genes influence the risk of developing certain diseases. The good news is diet and lifestyle affect the EXPRESSION of those genes, although not the genes themselves. Certain genes can be turned off or on in response to diet, exercise, and other lifestyle factors. So, genes aren’t destiny.

In this latest study, researchers fed various strains of mice with different genetics, several types of diets for six months at a time to see what impact it would have on their body weight and risk of disease. The diets the mice ate included a traditional Western diet, Mediterranean diet, a Japanese diet, or an Atkins-style low-carb diet. The researchers were careful to ensure the diets were similar to what humans consuming a similar diet would eat.

What they found was the impact each of these diets had on the mice varied with the particular strain of mice. In general, the “fast food” Western diet was detrimental to most strains, with mice that ate it gaining weight and developing fatty liver. Yet, surprisingly, one strain showed no ill effects. The Atkin’s style, low-carb diet caused some mice to burn more calories while some strains ate more on this type of diet and gained weight.  What the researchers concluded was there isn’t necessarily an ideal diet. The best diet is one that works with your genetics.

Another earlier study carried out by researchers at the University of California at Los Angeles also found variations in how mice responded to high-fat, high sugar diet, essentially a “junk food” diet. In response to this type of diet, some mice experienced a marked change in their gut microbiome while others didn’t. These changes, too, appears to be genetically influenced. We now know that gut bacteria play a role in obesity as well.

Of course, both studies were carried out in mice but the researchers believe these variations in response to particular diets likely apply to humans too. Thankfully, we’re learning more about the human genome every day. With this knowledge, a genetic test will eventually be developed that tells how you’re likely to respond to a particular diet. In fact, an entire field is built around the interaction between genes, health, and nutrition. It’s called nutritional genomics. With the help of research in this area, scientists are discovering how genes impact the response to a diet and how what you eat raises or lowers your risk of developing certain diseases.

Lifestyle Matters

No doubt, factors like insulin sensitivity, the status of other hormones, other health conditions, and your microbiome impact how you respond to a particular diet. Some of these factors are influenced by genetics but can also be affected by lifestyle. If you have poor insulin sensitivity, a high carbohydrate diet is more likely to cause weight gain and blood sugar elevations for you than for someone with good insulin sensitivity. If you have good insulin sensitivity, you may not gain weight or show a rise in your fasting blood sugar despite eating a junk food diet. This is similar to the mouse strain in the study that experienced no adverse effects from eating a Western diet. But insulin sensitivity is also shaped by lifestyle. Regular physical activity improves insulin sensitivity as does weight loss. So, the lifestyle you lead also indirectly affects how you respond to a particular diet.

What about the Mediterranean Diet?

There may not be one universal “best” diet for everyone, but for the majority of people, an eating plan that emphasizes whole foods over processed ones and one that contains at least some plant-based foods is best for weight control and for disease risk. A number of studies show a Mediterranean or DASH-style, one that emphasizes plant-based foods, including fruits, vegetables, whole grains, healthy fats, and nuts, and de-emphasizes processed foods and red meat, is linked with a lower risk of stroke, heart disease, obesity, type 2 diabetes, depression, and overall mortality. Until you’re able to get genetically tested to find out what YOUR optimal diet is, this way of eating has the strongest evidence in its favor.

It’s really hard to imagine that there are people who respond best to a diet high in sugar and processed foods. Even in the mouse study where one strain of mice didn’t develop obesity or signs of disease on a Western diet, it didn’t improve their health. Some people may be able to get by with eating processed foods and sugar without ill effects, at least in the short-term, this type of diet isn’t optimal for anyone’s health. Remember too, these studies only show the short-term effects of a particular type of diet. What happens when you eat a fast food diet over many years?

The Bottom Line

We’re all a little different and our unique variations mean we each respond uniquely to a particular style of eating. Until genetic testing comes along, your best bet is to eat a varied diet of whole foods and avoid empty calories from sources like sugar. You can argue that nature knows best when it comes to your health and well-being and what food manufacturers conjure up in a lab can’t hold a candle.


References: “Your Best Diet May Depend on Your Genetics”

National Institute of Health. “Genes, Junk Food and Weight”


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