Share on Pinterest
Most diets work but just temporarily. Getty Images
  • A new study finds most diets lead to weight loss and lower blood pressure, but that these desired effects largely disappear after a year.
  • In the study, people followed popular diets like paleo, keto, or Mediterranean. But after about a year, few kept the weight off.
  • People who are interested in losing weight, and maintaining it, need a more sustainable plan than simply going on a diet.

Weight loss and weight management are two very popular topics among Americans. Just look at any Instagram feed after the holidays or right before the summer season.

While dieting does produce impressive initial results, a new international study published in The BMJ shows that most diets, regardless of which one, lead to weight loss and lower blood pressure, but these desired effects largely disappear after a year.

Approximately 45 million Americans go on a diet each year.

The study was based on the results of 121 random trials with nearly 22,000 patients. The average age was 49, and each person followed a popular named diet — like paleo, keto, or Mediterranean — or an alternative control diet — like counting macros — and reported weight loss and changes in cardiovascular risk factors.

According to the study, evidence shows that most macronutrient diets, over 6 months, result in moderate weight loss and substantial improvements in cardiovascular risk factors like blood pressure. However, after 12 months, the effect on weight reduction and improvements in cardiovascular risk factors largely disappear.

A similar study from 2018, which followed 29 long-term weight loss studies, showed that more than half of the lost weight was regained within 2 years, and by 5 years, more than 80 percent of lost weight was regained.

What this suggests is that people who are interested in losing weight, and maintaining it, need a more sustainable plan than simply going on a diet.

Typically when someone starts a diet, they see weight loss right away, especially if they’re motivated and stick to that diet. But eventually, as the body loses weight, metabolism slows down and often people forget to adjust other behaviors.

“As you lose weight, your metabolism fights back against you and makes it harder to continue with that downward trend,” said Sharon Zarabi, RD, CDN, CPT, bariatric program director, Lenox Hill Hospital, New York. “We need to be more in tune with what works best for us, without feeling deprived, causing us to bounce back to prior unhealthy eating styles, whether it be macros, intervals of feeding, or portion control.”

“When people start out on a diet, they’re usually very gung-ho, and it may be easier for them to meal prep or keep a fridge stocked with healthy food,” said Despina Hyde-Gandhi, MS, registered dietitian at NYU Langone’s Weight Management Program. “As the weeks go on, whatever behavior they changed from initially starts to come back. We have to work with patients to make a total lifestyle change, not just a diet. That’s where we see a lapse in success.”

What’s a total lifestyle change? The recipe isn’t so mysterious. In fact, it’s pretty straightforward. It comes down to eating right and exercise. One of the biggest things that experts see with people looking to maintain weight is exercise. Calorie restriction is good, but to keep it off, physical activity and exercise have to increase to create lean body mass. The more lean mass a person has, the more elevated their metabolism can be.

“Doing what works for you is really important,” Hyde-Gandhi added. “There’s a lot of advice out there, from keto to paleo, and intermittent fasting. Some people feel great when they do these things, and some people feel lousy. You need to identify what works best for you and find balance in your meal structure.”

She recommends a rule of 50-25-25, where 50 percent of each meal is vegetables, 25 percent is lean protein, and 25 percent is high fiber carbs. “If you follow that formula, weight loss aside, you’ll feel well and your blood sugars will be balanced, which is helpful in maintaining your weight.”

Her other recommendations for staying healthy, weight loss or not, include:

  • 7 hours of sleep per night
  • 64 to 80 ounces of water per day
  • 150 minutes of exercise per week

“There is no one diet that works for all,” said Zarabi. “It’s what works best for you and is most sustainable for the long term. Any change you make to the daily food intake while lowering your total calories, will, in fact, assist in weight loss. The question is for how long.”