Do DNA-Based Diets Work?

Your Genetic Code and Fat Loss

The most effective diet is based on your individual genetics. Or is it? Here’s what you need to know before you buy one of these plans.

Healthy fat loss is all about consuming sub-maintenance calories, or spending more calories via activity, while keeping protein intake on the higher side. That’s about it. Of course, there are hundreds of ways to do it. The “best” plan for you comes down to preference and adherence.

Yet every few years, someone tries to hack this proven approach. We’ve had diets based on blood types and even diets based on astrological signs. There’s probably a diet based on your favorite Taylor Swift song. And these diets work, at least in the short term, but not for the reasons their proponents say they do. Rather, they work because they all boil down to eating less. Same plot, different novel.

Today, the new “best” diet for you is based on serious science: your genetic code. For $200 to $500, several companies will tell you exactly how to eat for fat loss based on your unique DNA. But does it work? Not really. Or at least not any better than the strategy outlined in the first sentence above. Save your money.

But, But, It’s Science!

It is science. Cool science, even. It just doesn’t seem to make a difference. Here’s some background:

Your genes don’t make you fat; your behaviors do. But there are genetic variations that might make it a little easier to get fat. For example, single-nucleotide polymorphisms (SNPS or “snips”) are found in the DNA between genes. Most are harmless, but some can play a role in disease if they affect the gene’s function. “Snips” of the leptin pathway seem to control hunger and how you burn calories, for example.

Now, the idea behind these DNA-based diets is that people respond better to certain macro ratios:

• Some people have carbohydrate-responsive genes (polymorphisms). They lose more fat on high-carb, low-fat diets.
• Some people have fat-responsive genes. They lose more fat on high-fat, low-carb diets.

Is That True? A New Study Took a Look

Researchers recruited 122 fat people and had them take a genealogy test. Based on 10 genes and their snips, they were deemed fat-responders or carb-responders and placed in a diet group, either a group that “matched” their genes or one that didn’t.

• Group 1: Fat-responders given a high-fat diet. This “matched,” so these folks should lose more weight.
• Group 2: Fat-responders given a high-carb diet. This didn’t match, so these folks should lose less weight.
• Group 3: Carb-responders given a matched high-carb diet, so they should do well.
• Group 4: Carb-responders given an unmatched high-fat diet, so they shouldn’t do well based on their genes.

All groups followed a 12-week plan where they consumed 750 calories below maintenance. The high-carb dieters ate 65% carbs and 20% fat. The high-fat dieters ate 45% carbs and 40% fat. All their diets were made up of 15% protein.

The Results

In a nutshell, the type of diet they were given, gene-matched or not gene-matched, didn’t make much of a difference at all.

The supposed fat-responders given the “right” diet lost 12 pounds, but those given the genetically “wrong” diet lost 11.5, which is statistically insignificant. Same with the carb responders, though there was a two-pound difference there (11 vs. 9) – still not considered significant since the average was 10 pounds, give or take. Also, there were no real differences in blood pressure and other metabolic health markers.

The researchers concluded, “We found no difference in weight loss between individuals on the genotype-concordant vs. genotype-discordant diet.”

How to Use This Info

T Nation contributor Dr. Bill Campbell says that personalized nutrition based on your genetic makeup is the future, but based on this study, we’re just not there yet.

If your fat-loss plan involves eating fewer calories and/or moving more – with the caveats of doing resistance training, eating plenty of protein, and choosing healthy foods – you’ll lose fat.

DNA-based fat-loss plans are, for now, science fiction.

Note: Thanks to Dr. Campbell for summing up this study in his excellent Body by Science newsletter.

Reference

1. Höchsmann, et al. “The Personalized Nutrition Study (POINTS):
   evaluation of a genetically informed weight loss approach, a Randomized Clinical Trial.” Nature Communications, 2023.