“Fat genes” don’t control your waistline… THIS does

I’ve spent a lot of my career trying to dispel the myth that genes make or break your health.

Because here’s the truth: You have a lot more control over how those genetics play out than you think.

Indeed, I just told you how you can conquer “bad genes” and outsmart dementia. But the same holds true for one of our nation’s greatest health threats: Obesity.

You may recall that I come from a family of obese people—most of whom have diabetes or heart disease (in addition to numerous other conditions that come as a result of being overweight). And I was obese myself, from childhood all the way through college.

Losing weight was the greatest struggle of my life. But I succeeded—and I’ve never gone back. So, really… anything is possible with consistency and effort.

That’s why, when people start talking about “fat genes,” I feel uniquely qualified to comment on the subject. But rather than talking about how these genes contribute to obesity, I’d like to issue a warning, instead…

Obesity changes your genes—and not for the better.

Methylation makes a difference

First and foremost, genetic influence actually has less to do with your genes, and more to do with how those genes manifest themselves.

You see, in order for genes to influence your health, they require “expression.” This distinction is the basis of a new field of study called “epigenetics.” Epigenetic changes are what determine whether those deadly obesity, heart disease, and diabetes genes rise to surface… or if they stay silent.

But unlike other hereditary markers, epigenetic changes aren’t carved in stone ahead of time. And they can be reversed.

In fact, all sorts of daily factors—like your diet, your activity level, or exposure to environmental toxins—can lead to epigenetic changes. These changes can either protect you from a lifetime of chronic illness, or send you to an early grave.

DNA methylation, specifically, is an epigenetic process that modifies the function of the DNA. Cells use this process to control gene expression, for better or for worse. (In other words, DNA methylation can turn genes “on” or “off”.)

As you might imagine, that can come with some pretty far-reaching consequences. And in the case of obesity, none of them are good.

Obesity alters your genes

Researchers from the University of Malaga recently found that methylation levels in Lipoprotein lipase (LPL)—a gene involved in lipid metabolism—are higher in metabolically unhealthy obese people than in healthy people.

This gene decides where the fat you eat goes—whether your body will store it or use it as fuel. As a result, when things go haywire with LPL, it will take your triglyceride levels with it. (Those are the actual bad fats you need to worry about.)

But the news gets worse: The same study found lower rates of DNA methylation on genes linked to inflammation, such as tumor necrosis factor (TNF). This could cause certain genes to be overactive—leading to chronic inflammation, and all of the diseases that come with it. Which partially explains the links between obesity and conditions like diabetes, heart disease, and cancer.1

Plus, another recent large-scale study showed that a high body mass index (BMI) can lead to epigenetic changes on at least 200 locations in the genome. (Just to be clear, these changes weren’t the cause of the weight gain… they were the effect of it.)

And once again, the biggest changes were in the expression of genes related to lipid metabolism and inflammation.2

Weight loss flips the switch

The good news is, these changes appear to be at least partially reversible with weight loss.

In fact, one study found that gastric bypass surgery was able to alter gene expression in people who lost weight after surgery—restoring genes related to metabolic health back to healthy conditions.3

More specifically, researchers found that methylation changes in two genes related to blood sugar and fat metabolism were both correlated with obesity. But these changes were reversed with post-surgery weight loss.

In another study, published in the European Journal of Clinical Nutrition, Brazilian researchers found significant differences in DNA methylation among severely obese women compared to women with normal BMIs.

But, after following a low-calorie diet for six weeks (to the tune of 1,200 calories per day), the obese women lost weight—and their DNA methylation profiles changed dramatically, too.

In fact, researchers found changes at more than 16,000 sites in the genome, affecting more than 9,200 genes—many of which had links to cancer.4

Of course, you know how I feel about both weight loss surgery and low-calorie diets. Both might be effective solutions in the short term, for some people. But they do absolutely nothing to address long-term weight management—which is why they often fail in the end.

If you really want to lose weight and keep it off, a high-fat, low-carb, Mediterranean-style plan that’s rich in lean protein and fresh, whole foods (like my A-List Diet) is the way to go.

But that’s still only half the battle, at least where DNA methylation is concerned…

Just keep moving

In addition to following a balanced diet, exercise can reverse epigenetic changes to the DNA, too. Even in small doses!

Swedish researchers examined methylation changes in fat cells among a group of 23 slightly overweight and sedentary middle-aged men who attended spinning and aerobics classes for six months.

They were supposed to attend these sessions three times a week—but on average, they only went 1.8 times weekly. Nevertheless, the researchers still found epigenetic changes in nearly 7,000 genes—including genes linked to type 2 diabetes and obesity.5

(If even small amounts of exercise can protect the DNA of younger people who are only slightly overweight, just imagine what regular, consistent exercise can do for someone older and obese!)

Here’s the bottom line: When it comes to your health, no single outcome is carved in stone. You can’t control your genetic makeup—but you can control your lifestyle choices.

So choose wisely, and consistently, every single day. Your health relies on it, in more ways than one.


  1. Castellano-Castillo D, et al.Altered Adipose Tissue DNA Methylation Status in Metabolic Syndrome: Relationships Between Global DNA Methylation and Specific Methylation atAdipogenic, Lipid Metabolism and Inflammatory Candidate Genes and Metabolic Variables. Journal of Clinical Medicine, 2019; 8 (1): 87 DOI: 10.3390/jcm8010087 
  2. Wahl S, et al.Epigenome-wide association study of body mass index, and the adverse outcomes of adiposity. Nature, 2016; DOI: 10.1038/nature20784 
  3. Barres R, et al. “Weight Loss after Gastric Bypass Surgery in Human Obesity Remodels Promoter Methylation.”Cell Reports, 11 April 2013 DOI: 10.1016/j.celrep.2013.03.018 
  4. Nicoletti, C.F. et al. “DNA methylation pattern changes following a short-term hypocaloric diet in women with obesity.Eur J ClinNutr., 2020.   
  5. RönnT et al. A Six Months Exercise Intervention Influences the Genome-wide DNA Methylation Pattern in Human Adipose Tissue. PLoS Genetics, 2013; 9 (6): e1003572.