Study under review: Preventing weight gain in adults: A systematic review and meta-analysis of randomized controlled trials
About 40% of Americans gained more than a pound during the peak restrictions of the COVID-19 pandemic, and half of those who gained more than 5 pounds maintained or continued to gain weight afterward. This is why preventing weight gain in the first place has been thrust in the spotlight as a key strategy to manage population-level trends in obesity. Considering the time- and resource-intensive nature of weight loss, and the high likelihood of regaining lost weight, preventing weight gain — a strategy that has not been as thoroughly studied — is paramount to address the global obesity challenge.
Weight gain, which generally refers to an accumulation of fat tissue, is a gradual process. In the U.S., people gain about 1.5 pounds (670 grams) per year, with weight gain accelerating around holidays. Assuming a continuous linear weight gain, the yearly rate is driven by a surplus of just 190 to 220 calories per day. The average person gains the bulk of their weight in their 20s, 30s, and early 40s, and this rate slows later in life. In already overweight individuals, gaining 2.2 lbs (1 kg) per year over 10 years increases the risk of developing type 2 diabetes by 49%, compared to people who maintain their weight. Similarly, the risk for cardiovascular disease increases by 1.4% with every pound gained. Assuming that weight is on a slow upward trend, then it may only take small, consistent changes in weight-related behaviors to help prevent obesity and related cardiometabolic diseases.
The most recent systematic review of weight gain prevention studies among adults of all ages was published in 2009. With only nine studies, a quantitative meta-analysis or exploratory secondary analyses were not possible. Most importantly, though, the authors were not able to identify the traits that made preventive interventions effective. In 2020, another systematic review of behavior changes to prevent weight gain and strategies to lose weight among young adults was published. With a singular focus on behavioral techniques for young adults, this systematic review provided insight on effective behavior change techniques but was limited in scope to young adults. In the systematic review and meta analysis under review, the authors aimed to answer two questions: is it possible to quantify how successful weight gain prevention programs are for adults? And, what are the characteristics of successful programs?
Preventing weight gain is a promising public health strategy because strategies for maintaining weight are not as restrictive as weight loss interventions and not subject to the challenge of weight loss maintenance. Studies suggest that simple, consistently implemented lifestyle modifications can effectively limit the increase in weight seen in almost all parts of the world. The meta-analysis at hand was designed to quantify the effects of these strategies, and identify patterns characterizing the most successful anti-weight gain interventions.
Other Articles in Issue #81 (July 2021)
Will cardio hurt your strength gains? It depends on your training level!
This recent meta-analysis suggests that concurrent endurance and resistance training only hurts strength gains for more experienced athletes.
Fit and full: Exercise does not reliably affect appetite or calorie intake
According to this meta-analysis, exercise may boost caloric intake a tad, but not enough to matter.
Deeper Dive: What are the differences between people who lose an expected amount of weight on a restricted diet and people who don't?
This retrospective analysis explored two possible causes of less-than-expected weight loss during caloric restriction: impaired fat oxidation and changes in resting energy expenditure.
Nulls: March-April 2021
A quick run-through of recently published studies that didn't find evidence of an effect.
Safety Spotlight: Omega-3 fatty acid supplementation can increase the risk of atrial fibrillation
Here's a quick rundown of a recent meta-analysis which explored whether EPA and DHA supplementation can increase the risk of atrial fibrillation. Currently, the answer appears to be "yes."
Deeper Dive: What is the best weight loss strategy for treating knee osteoarthritis?
Bariatric surgery helped the most, probably because it helped shed the most pounds.
Zest with zinc: Fighting fatigue with zinc supplementation for older adults
This trial examined whether zinc supplementation could put the pep back in older adults' step. While the results look promising, the fact that it wasn't blinded or placebo-controlled means more follow-up is needed.