If you've tried to lose weight, the standard advice is to eat less and move more, allowing the extra pounds on your body to disappear. It’s the weight-loss mantra doctors have been touting for decades, so why has obesity continued to skyrocket in the U.S.?
More than 40% of American adults are considered obese, according to the Centers for Disease Control and Prevention.
Now, a group of obesity doctors and scientists argue that calorie restriction could be causing more harm than good.
The body fights back when people eat less, said Dr. David Ludwig, professor of nutrition at Harvard School of Public Health, who leads the team. Restricting calories not only causes people to be more hungry, but also slows down metabolism, he noted.
“While people can lose weight over the short term, very few people can manage to ignore their hunger and fight through those metabolic problems to maintain their weight loss,” Ludwig told TODAY.
Instead, Ludwig and his colleagues suggest a new approach — what they call the carbohydrate-insulin model. If overeating isn’t fueling obesity, stop counting calories and just cut carbohydrates to control your insulin levels.
“Insulin — you can think of (it) as the ultimate fat cell fertilizer. Too much insulin, fat cells get programmed to hoard calories. So there aren’t too many calories in the blood stream. And that’s why we get hungry,” Ludwig said.
Low-carb diets have become increasingly popular in recent years. Most involve cutting out refined carbs, including bread, rice and sweets. The focus instead is on protein and healthy fats, such as avocados and nuts.
The popular ketogenic diet is a more extreme form that restricts carbs to between 30 and 50 grams a day, which is a challenge for many Americans considering that’s a single bagel has 48 grams of carbs alone.
But more research has found low-carb diets are not only effective, they’re sustainable.
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Jennifer Haines, 42, said being overweight left her feeling uncomfortable, tired and depressed. She tried diet after diet, including counting calories, but nothing really worked because she couldn’t stick with any plan.
Three years ago, she joined a study run by researcher Jeff Volek, a professor in the department of human sciences at Ohio State University, who’s been studying low-carb diets for 25 years.
After six weeks on his low-carb diet, Haines lost 20 pounds and kept going. She has now lost 88 pounds total since starting the eating plan in 2019.
“Within the six-week study that I did, I looked like a completely different human,” she said. “It was wonderful.”
The diet wasn’t easy at first because Haines was forced to cut out her favorite foods, including pasta, bread and potatoes. But seeing results was the motivation she needed. She called keto a lifestyle change, not a diet.
Imaging of her body's fat stores before and after the adopted the new low-carb eating plan showed a difference just six weeks later.
“People have a remarkably healthy response to these diets,” Volek said. “The body responds in a really elegant way. When you limit carbohydrates, the body gets really good at burning its own body fat because it doesn’t have a lot of sugar to burn for fuel.”
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When people get the diet right by limiting carbs, eating moderate amounts of protein and embracing fat, they feel full and naturally restrict calories without having to count them, Volek added.
He and his colleagues consider the weight loss a side benefit because they often use the low-carb diet to treat Type 2 diabetes, he noted.
Volek’s studies have found people on low-carb diets can lose more than 10% of their body weight and keep it off, something that Haines says has been a game-changer.
“I feel great. It’s easy for me to get up. It’s easy for me to go to sleep. I feel a lot more comfortable with myself,” she said.
This new approach also eliminates some of the stigma surrounding obesity, which is typically treated as a behavioral problem. Doctors often assume people are overweight because they eat too much or have low willpower. This approach takes the blame away from the patient and looks at obesity as a biological problem, focusing on regulating the hormone insulin.
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Volek and his team at Ohio State are also studying the benefits of low-carb diets on other diseases and conditions, including for some types of cancer, as well as for mental health.
Depending on which version of the eating plan you do, whether it’s keto or just a lower carb diet, you can still eat some carbs — it’s just a matter of tracking them closely.
As always, talk to your doctor to make sure an eating plan is right for you and remember: there is no one-size-fits-all diet. The best is the one you can stick with long-term.