“We want to recommend that people keep their ideal body weight, and if they tend to lose weight, they should try to keep their body weight from fluctuating,” says one of the study’s authors, Tae Jung Oh, MD, an assistant professor in the division of endocrinology and metabolism in the department of internal medicine at Seoul National University’s Bundang Hospital in South Korea. Dr. Oh and his team analyzed the health information of 3,678 men and women ages 40 to 96, from the Korean Genome and Epidemiology Study. The researchers measured participants’ weight and body mass index (BMI) two times per year, and considered overweight as a BMI of 25, which aligns with the National Heart, Lung, and Blood Institute’s (NHLBI) definition of overweight in the United States. RELATED: Why BMI Is Flawed and Other Ways to Measure Body Weight Researchers used a scientific formula called average successive variability to measure participants’ weight changes, and then compared them with participants’ death rates. Over a median 14-year follow-up, they observed that 173 people whose weight fluctuated the most (9.4 percent among that group) died, while 90 of the participants whose weight fluctuated the least (4.9 percent among that group) died. Of the 263 total deaths, 43 were attributed to heart disease.
Why Even a Little Weight Loss May Be Protective for People Who Are Overweight
The researchers found that participants whose weight changed the most tended to be obese and have higher blood pressure and hemoglobin A1C (HbA1C) levels at baseline than those with low body weight changes. HbA1C is a two- to three-month average of blood sugar levels that is used to diagnose diabetes. Despite those individuals’ weight fluctuations, they saw a lower risk of diabetes at the study outset. But those at baseline with a BMI of 25 or less, which is considered normal or underweight per the NHLBI, saw a higher risk of diabetes from their weight changes. Mitchell Roslin, MD, who is the chief of obesity surgery at Lenox Hill Hospital in New York City and was not involved in the new study, says “those who were overweight and obese were more likely to lose and gain. The fact that the obese who had variability had less diabetes is probably due to some weight they lost at the time.” He says weight loss can help lower insulin resistance, the hallmark of type 2 diabetes, among people who are overweight or obese, so that may explain their lower risk for diabetes. Dr. Roslin also speculated that the normal-weight people may have been more genetically at risk for diabetes, in which case their glucose fluctuations may have driven the weight gain. Other studies, as reported by the Mayo Clinic, have found that yo-yo dieting may increase weight and body fat, but may not necessarily increase the risk of type 2 diabetes.
Why It’s So Hard to Maintain Weight Loss
One- to two-thirds of weight lost is often regained within one year, and almost all the lost weight is regained within five years, according to a February 2015 study in Obesity Reviews. One possible reason: After a person loses weight, the body typically expends less energy during rest, exercise, and daily activities. According to the authors of a statement published in August 2017 in Endocrine Reviews, the “reduced body weight increases hunger as well, creating a ‘perfect metabolic storm’ for weight regain.” Though this study involved participants in South Korea, Americans’ propensity to rely on fad diets that result in quick weight loss may contribute to weight cycling that is even greater than the changes seen in the study. Jan Rystrom, MD, a registered dietitian and diabetes educator at Swedish Medical Center in Seattle who was not involved in the study, says the mean weight change in the study was 2.8 pounds (lb). “That’s a very small amount,” she says. “Hardly what North Americans might consider ‘weight cycling.’” Not to mention, there’s conflicting research on the health effects of weight cycling, according to a review published in November 2015 in Obesity Reviews. RELATED: 21 Tips for Weight Loss That Actually Work
How to Help Keep Off the Lost Weight
The CDC recommends shaving off pounds, such as 5 to 10 percent of your total body weight, to help lower your cholesterol, blood pressure, and blood sugar. For instance, if you’re 200 lb, to lose 5 percent of your body weight, you’d aim to drop 10 lb. To lower the number on the scale, you’ll want to avoid quick fixes and instead aim to lose 1 to 2 lb per week steadily to help increase your chances of success, the CDC suggests. “The take-home message should be that a healthy diet is essential,” says Dr. Roslin. “Changing to a healthy food plan is a strategy, but choosing short-term crash diets that get fast but not lasting weight loss is not.” RELATED: A Detailed Guide to the Mediterranean Diet Dr. Rystrom says the investigation was significant in the sample size and number of years covered. But the data came from a self-reported questionnaire and was not collected clinically. Physical activity and nutritional information were not part of the report. The authors also noted that they could not determine if weight loss was intended or may have been due to another cause, such as chronic disease. “This is an observational cohort study,” says Oh, “so further study should be performed to unveil the hidden mechanism [as to why weight fluctuation increases mortality].”
