Even Nonobese Adults May Benefit From Cutting Calories

Reducing caloric intake by 25% over 2 years was associated with improved health-related quality of life outcomes in nonobese adults, according to data published in JAMA Internal Medicine.¹

Although calorie restriction has been shown to increase longevity in some species, concerns remain about potential negative effects on certain quality-of-life aspects in humans.

To learn more, researchers conducted a clinical trial at 3 academic research centers to evaluate the impact of calorie restriction on quality of life outcomes that are thought to be negatively affected by calorie restriction, including decreased libido, lower stamina, depressed mood, and irritability.

The researchers administered self-report questionnaires to measure mood (Beck Depression Inventory-II and Profile of Mood States), quality of life (Rand 36-Item Short Form and Perceived Stress Scale), sleep (Pittsburgh Sleep Quality Index), and sexual function (Derogatis Interview for Sexual Function—Self-report).

A total of 218 participants (69.7% women; mean age, 37.9 years) with a mean BMI of 25.1 were randomly assigned almost 2 to 1 to 2 years of 25% calorie restriction or an ad libitum control group.

The calorie restriction and ad libitum groups lost a mean of 7.6 kg and 0.4 kg, respectively, at 24 months (P<.001),¹ according to the data.

Results showed that the calorie restriction group had significantly improved mood, reduced tension, general health, and sexual drive and relationship at 24 months and improved sleep duration at 12 months, as compared with the ad libitum group (P<.05 for all).¹

Additionally, data linked greater percent weight loss at 24 months in the calorie restriction group with increased vigor and less mood disturbance, improved general health, and better sleep quality.¹

The researchers also noted that in the intention-to-treat analysis, sex hormone-binding globulin levels increased in men in the calorie restriction group vs the ad libitum group at 12 and 24 months (P<.001), while free testosterone levels decreased in the calorie restriction group vs the ad libitum group at 12 but not 24 months.¹ Changes in luteinizing hormone, total testosterone, and follicle-stimulating hormone levels were not significantly different between groups.¹

The study was limited in the fact that the sample was comprised of healthy people, which limited variability, and was predominantly female and white, which limited generalizability.

“Calorie restriction among primarily overweight and obese persons has been found to improve QOL [quality of life], sleep and sexual function, and the results of the present study indicate that 2 years of CR [calorie restriction] is unlikely to negatively affect these factors in healthy adults; rather, CR is likely to provide some improvement,” the researchers concluded.

Strategies for Preventing Weight Gain

In a second study, researchers evaluated interventions to prevent weight gain in young adults. They noted that this age group is gaining weight the fastest and that weight gain also has the strongest associations with critical outcomes such as cancer risk and mortality than weight gain at later ages.²

“Previous efforts to prevent weight gain during adulthood, particularly in young adults, have had limited success,” the researchers wrote. “Although positive effects are often observed initially, few studies have observed participants for 2 to 3 years and long-term differences between intervention and control are rarely significant. Moreover, many of these programs have been implemented in college courses, limiting generalizability.”

The researchers randomly assigned 599 participants (22% men; mean age, 27.7 years) with a mean BMI of 25.4 to control, an intervention that included self-regulation plus small changes, or an intervention that included self-regulation plus large changes based on frequent self-weighing to prompt behavior changes. Small changes focused on reducing caloric intake and increasing physical activity, both by approximately 100 calories per day. Large changes focused on losing 2.3 kg to 4.5 kg initially to offset expected weight gain.