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Do These Genes Make Me Look Fat?

There is a genetic factor to obesity, but it doesn’t set our destiny.

Key points

  • It is not genes that affect obesity, but gene activity.
  • Which genes are active depends on epigenetics.
  • Some epigenetic switches are determined by diet and the microbiota, giving us leverage.
Genes are not destiny.
Source: maselkoo99/iStock

When a random worker honeybee is selected to become a queen, she is nothing special. But after dining on royal jelly, she doubles in size to become a queen capable of giving birth to a thousand bees every day. Even more impressive, she can live for 6 years, some 50 times longer than a worker bee. For a human, that would be the equivalent of being 11 feet tall and living for 3,500 years! The idea that a mere change in diet could have such an impact is mind-boggling.

How Do Genes Work?

Our DNA, inherited from our parents, is a cookbook containing around 20,000 recipes that are needed to create and operate a cell. In this metaphor, genes are the recipes; they provide step-by-step instructions for assembling the proteins that construct our bodies and our minds.

We all start out as a tiny ball of identical cells. These are stem cells with the potential to become any cell in the body. Each stem cell contains the complete cookbook, with all genes at the ready, but it doesn’t stay that way for long. To make a complex animal, each tissue requires a unique set of proteins that creates the difference between, say, a skin cell and a liver cell.

As we develop in the uterus, these tissues begin to differentiate, starting with an inside and an outside, but gradually growing more convoluted. Even though every cell in our body contains all of our genes, most of them are silenced during differentiation. The mechanism that turns genes on and off is called epigenetics.

Even after we are born, genes continue to be switched on and off by hormonally driven epigenetics, guiding us through puberty. Think of epigenetics as dog ears on the cellular cookbook, marking just the genetic recipes that are needed by each cell.

Your Human Genes

We know that a few dozen genes—involved with immunity, metabolism, and eating behavior—are associated with obesity and insulin resistance. But twins with identical genes don’t always share the same fate, so genes alone can’t account for all cases of obesity. Thus, epigenetic factors may be at play.

Not all epigenetic effects are beneficial. Early exposure to environmental chemicals, including lead, cadmium, and certain plastics, may predispose people to obesity by improperly switching genes. Epigenetic changes are more or less permanent, which is usually good: You don’t want your liver to suddenly sprout fingers. But that lingering influence also means that bad epigenetic effects acquired in childhood can persist into adulthood. Get epigenetically fat as a child, and you may have to fight it forever. More amazingly, those epigenetic changes can be passed on to your children and even possibly your grandkids.

But epigenetic changes are sometimes reversible. If you can turn a gene on with a nutrient like royal jelly, you might be able to turn it off with another. The idea that we could control these semi-permanent epigenetic changes with diet is remarkable. The study of this phenomenon is called nutrigenomics.

One of the chemicals involved with epigenetic alterations is butyrate, which has the ability to tamp down inflammation. That can improve insulin regulation and reduce obesity. Butyrate is a simple short-chain fatty acid, and you can buy it as a supplement. But here’s a tip: The trillions of bacteria in your gut can also produce butyrate if you feed them right.

Bacterial Genes

Your gut contains about three pounds of bacteria representing a wild assortment of species, each consuming and secreting different chemicals. This is your microbiota, and it is a bustling Lilliputian metropolis located mostly in your colon. It is, essentially, an unsung extra organ—albeit a strange one that renews its composition daily.

Humans have some 20,000 genes or so, but your gut microbes have at least a hundred-fold more. Thus, genetically, you are less than 1 percent human. Among those genes are those that produce short-chain fatty acids like butyrate. And that means that your microbes can make epigenetic changes to your body. Among the arguments for treating your gut microbes with respect, that has to be at the top of the list.

What to Do

So how do you convince your gut microbes to produce short-chain fatty acids? You feed them fiber.

Fiber is composed of chains of sugars called oligosaccharides. While sugar is instantly absorbed by your gut, these oligosaccharide chains are resistant to digestion—by you, at least. But oligosaccharides are an ideal food for your gut microbes.

It is surprisingly easy to find oligosaccharides in food. They are abundant in onions, beans, raspberries, apples, and other veggies and fruits. Food manufacturers have spent decades creating delicious foods that are largely fiber-free. They bear a big part of the blame for our low-fiber diets and the epidemic of obesity on the planet.

As well as feeding our microbes, we can directly affect our epigenetics with flavonoids and oils. Flavonoids are plant molecules that activate genes to reduce inflammation and improve glycemic control. And omega-3 and omega-6 oils can have direct epigenetic effects, acting almost like hormones. Molecules like these can infiltrate your cells, one by one, and repair broken epigenetic markers.

For many of us, the veggie section in the store is like a foreign land with a strange language. What in the world is celeriac or escarole? But you should take some time to acquaint yourself with the vegetable aisle and spend less time in the comforting center of the store with all its enticing low-fiber packaged goods.

Repairing your gene activity requires dedication, but, over time, inflammation can be reduced, improving your metabolism and silencing your obesity genes. As a bonus, when your gut has healed by you eating properly, everything in your body works better. You feel more energetic, your joints are more limber, and you can even think better.

It can be difficult to start eating more veggies and whole foods, so feel free to supplement. Probiotics are live bacteria that can augment your microbiota, and prebiotics are oligosaccharides that can feed your existing home-grown microbes. You can get both pro- and prebiotics from fermented foods like kimchee, sauerkraut, and yogurt. These foods are as close as we are likely to get to royal jelly, keeping us in optimal health.

You can’t do much about the genes you were born with, but diet provides a way to affect their activity, granting you a powerful lever over your future self. It can take some time, but a change in diet has the potential to build a better you, one cell at a time.


Herrera, Blanca M., Sarah Keildson, and Cecilia M. Lindgren. “Genetics and Epigenetics of Obesity.” Maturitas 69, no. 1 (May 2011): 41–49.

Mead, M. Nathaniel. “Nutrigenomics: The Genome–Food Interface.” Environmental Health Perspectives 115, no. 12 (December 2007): A582–89.

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