To Get Bigger, 23andMe Is Watching A Hundred Thousand People Diet

How the genetic testing company is tapping its customers to power the largest study yet on diet, exercise, and DNA—and what it might do with all that data.

To Get Bigger, 23andMe Is Watching A Hundred Thousand People Diet
[Photo: Rawpixel]

23andMe validated countless ancestral claims (and genetic ties to St. Patrick’s Day) with its DNA tests, and now the company is focusing on something quite different: the scale. In December, the biotech pioneer announced a weight loss intervention study to better understand the relationship between genetics and lifestyle factors such as diet and exercise.


“We suspect that there may be underlying genetic architecture that may make it easier for some individuals to lose weight,” says Liana Del Gobbo, 23andMe’s lead scientist on the study.

The goal would be to help people better understand what methods work for their bodies. Basically, an end to the constant search for the perfect diet.

Even though the scientific community identified over 150 genetic variants associated with weight–and despite a string of expensive and unscientific DNA-based diets–there isn’t much evidence so far of a connection between genes and weight loss. With this crowdsourced study–what may be the most comprehensive effort yet to understand these links–23andme is hoping to change that.

The Mountain View, California-based company recruited 100,000 individuals between the ages of 18 and 70 from its existing 3 million-customer database. For three months, participants follow one of three plans: low-carbohydrate diet (“this one is enormously popular,” notes Del Gobbo), high-fiber diet, and exercise-focused physical activity.

Participants monitor their daily habits and fill out surveys on their food preferences, cravings, sleep quality, meal timing, even stress levels. Every other week, 23andMe researchers question them on how their diet and physical activity changed, followed by a six and 12-month follow-up. Participants are also given tips, meal suggestions, as well as videos to learn more about their plans.

It’s an ambitious study, one that dwarfs the test pools of more controlled studies. In general, trials that have been conducted in brick and mortar facilities–institutional or academic settings–haven’t been able to recruit enough participants to explore genetic variants. Their numbers traditionally fall under a thousand people.


The trade-off, of course, is the inability to control and closely monitor the various factors affecting the group. It’s self-reported, with 23andMe trusting people to comply with guidelines via an online questionnaire.

“It’s really challenging because you know people are out in the free world. They’re buying their own food,” explains Del Gobbo.

Related: DNA-Based Diet Advice Is Big Business With Little Scientific Support 

Exercise plan participants, meanwhile, are given non-prescriptive exercise goals. 23andMe provided the American Society of Sports Medicine’s guidelines, meaning folks can do a host of physical activities provided it’s 150 minutes of moderate aerobic activity plus strength training twice a week.

“The diets and intervention plans were designed to allow for some flexibility because people have different lifestyles,” explains Del Gobbo. “It’s hard to try to convince everyone just to do yoga or only to eat certain foods; people have various physical limitations, preferences, or food restrictions that we want to be respectful of.”

There’s room for confusion with such broad instruction. A Reddit thread about the study shows some participant frustration, with one commenter exclaiming, “I was assigned the low-carb group, and I was really hoping for more guidance from them on the expected eating plans. What does low carb mean? 0g? 50g? 80g?”


Adherence issues also include limitations such as the flu–or a mojito-heavy honeymoon. A week or two off the plan doesn’t necessarily invalidate one’s participation. The study is purposely permissive, asking people to abide by rules and share data to the best of their abilities.

The research team is aware of the drawbacks that come with conducting a trial via the internet, and the doubts that plague it. Critics also say that despite the large pool, the study won’t attest for the potentially hundreds of thousands of factors that determine weight loss. This includes genetic predispositions, but also socioeconomic or circumstantial factors, like access to fresh, healthy foods.

“There’s a lot of moving parts,” concedes Geoffrey Benton, 23andMe director of health R&D, “not everything is going to work perfectly, whether it’s adherence or engagement, but we’re going to learn a ton from this. We are going in eyes wide open that there are going to be some speed bumps along the way.”

This isn’t the first time 23andMe has ventured into uncharted territory. In 2016, the company crowdsourced over 450,000 customers to study genetics tied to depression. Last summer, it partnered with The Milkin Institute and Lundbeck, a global pharmaceutical company, to study 25,000 participants for major depressive disorders and bipolar disorders. There’s also ongoing Parkinson’s Disease research with academic and biotech partners. It’s a testament to 23andMe pushing more and more into areas of consumer health.

So is the goal to one day have people spit in a tube and be prescribed a personalized diet plan? Perhaps. Del Gobbo doesn’t reject the possibility, but she admits that personalized medicine for health and wellness is very much in its infancy (despite the surge of kits on the market). Mapping out weight loss and its connection to non-genetic lifestyle factors is a tricky, multi-faceted question, one that will take years to begin to answer.


“This is clearly not going to be a single trial that solves the problem or provides us with a solution to personalization,” stresses Benton. “But it’s the first step.”

Ultimately, 23andMe envisions itself partnering with companies providing genetic guided weight loss plans or fitness and diet apps. 23andMe will be the research arm, lending its data to products.

Until then, the research team is busy monitoring and engaging with participants, which includes many of their own family members. Del Gobbo’s husband is in the low-carb study, and already benefitted from its lax approach: On day one of the intervention, he refused a potato Del Gobbo had baked for him.

“It’s been exciting to see participants and my husband take it really seriously get really into it,” she laughs. “I love that enthusiasm. But seriously, a potato now and then is OK. Really. I promise.”

23andMe is an honoree on Fast Company’s 2018 World’s Most Innovative Companies list.


About the author

Rina Raphael is a writer who covers technology, health, and wellness for Fast Company. Sign up for her newsletter on the wellness economy here: