Even healthy, young, slim people can benefit from cutting 300 calories a day from their diet — a simple lifestyle change that can lead to a big payoff in heart health, a new study has found.
The strategy could reduce the “ravages” of cardiovascular disease, diabetes and obesity, the authors wrote, possibly boosting longevity.
People who followed the calorie-restriction diet for two years had a lower blood pressure, lower total cholesterol, lower risk of metabolic syndrome and improvements in insulin sensitivity, researchers reported Thursday in The Lancet Diabetes & Endocrinology.
They also lost an average of about 16 pounds, 71% of which was fat. It’s the first medium-term study of calorie restriction in humans.
“The message from this paper is: Anything is better than what we’re doing now. Even more modest caloric restriction may have benefits,” Dr. William E. Kraus, the lead author, a cardiologist and professor at the Duke University School of Medicine, told TODAY.
“[Cutting] 300 calories is very doable.”
The study followed 218 people who were randomly assigned to either cut 25% of calories from their regular diet for two years, or to continue eating just as they always had during that period.
The participants were 21-50 years old, healthy and slim or slightly overweight. Various aspects of their health were measured at baseline, including blood pressure, cholesterol, metabolic syndrome risk and insulin resistance.
The people who followed the diet had their meals prepared at clinical centers for the first month to understand what a 25% reduction in daily calories looked like. They were also counseled on the basics of calorie restriction — eating a 6-ounce steak rather than an 8-ounce cut, for example. But the researchers didn’t try to change their basic underlying diet, Kraus.
The dieters also attended counselling sessions during the first six months of the study.
People in the control group continued their normal eating regimen without any dietary intervention or counselling.
The dieters were asked to maintain the 25% cut in their daily calories for two years, but they averaged only about half that, 12% — amounting to eating 300 fewer calories a day. Even with that reduction, their cardiometabolic risk factors were “significantly reduced,” the study noted. They also lost about 10 percent of their body weight, most of it fat.
Why would calorie restriction be so beneficial?
“That’s the million-dollar question, it’s something we really don’t know,” Kraus said.
“It’s not all just due to the weight [change]. There is something else about restricting calories that seems to have benefits on cardiometabolic factors that we don’t really understand.”
But the study also showed how challenging it is for people to eat less over the long term, noted Dr. Frank Hu, chair of the department of nutrition at the Harvard T.H. Chan School of Public Health.
Their dropout rate was more than three times higher than that of people in the control group. The strategy also required reliably counting calories every day.
Combining calorie restriction with other strategies like intermittent fasting, a low-carb diet or the Mediterranean diet could help people stick with a healthy lifestyle that ensures a lean body over the long term — “the optimal way to promote longevity,” Hu wrote in a commentary that accompanied the study in The Lancet Diabetes & Endocrinology.
How to eliminate 300 calories a day:
The first thing Kraus tells his patients who need to lose weight is:
- Stop eating anything after dinner. Just don’t snack after pushing away from the dinner table.
“That will usually take care of the problem,” he said. “People come to my clinic and tell me they have a bowl of ice cream before they go to bed and I just have a fit because those calories are not going to be used — they’re going to be stored — and it’s excess caloric intake they don’t need.”
- Identify a non-essential component of your diet you can easily skip. It’s usually a piece of bread, which has 100 calories, Kraus said.
- At least initially, count calories every day so you know what 300 calories look like and what you’re actually eating. After a while, you’ll instinctively know what to eat and what to skip.
The calorie-restriction diet can take a lot of mental focus and discipline to maintain, but can be achieved by eating a variety of low-calorie fruits and vegetables, fiber-rich starch, lean plant and animal proteins, and heart-healthy fats, noted NBC News Health and Nutrition Editor Madelyn Fernstrom.