Adults with obesity who participated in weight-loss diet interventions had a lower risk for premature death compared with control groups, but evidence related to differences in cardiovascular and cancer mortality risks was less strong, according to meta-analysis findings.
“Weight-reducing diets, usually low in fat and saturated fat, may reduce premature all-cause mortality in adults who are obese,” Alison Avenell, MD, of the health services research unit at the University of Aberdeen in Scotland, told Endocrine Today. “Most of the reducing diets also gave advice to increase exercise or provided an exercise program to attend. We do not have evidence to establish whether other forms of weight-reducing diets have this effect, and we cannot dissociate the effects of weight loss from the use of low-fat diets in our study.”
Avenell and colleagues conducted a systematic review and meta-analysis of 54 randomized controlled trials with 30,206 participants to assess whether weight-loss interventions that include a weight-reducing diet affect all-cause, CV and cancer mortality, CVD, cancer and body weight in adults with obesity.
All trials consisted of dietary interventions targeting weight loss, with or without exercise advice programs compared with a control intervention.
Thirty-four trials included data on all-cause mortality, and researchers observed high-quality evidence that there was a decrease in premature mortality with weight-loss interventions (685 events; RR = 0.82; 95% CI, 0.71-0.95). Moderate-quality evidence was observed for an effect of weight-loss intervention on CV mortality (8 trials; 134 events; RR = 0.93; 95% CI, 0.67-1.31), and very low-quality evidence was observed for an effect on cancer mortality (8 trials; 34 events; RR = 0.58; 95% CI, 0.3-1.11).
High-quality evidence on participants developing new CV events was reported in 24 trials (1,043 events; RR = 0.93; 95% CI, 0.83-1.04), and very low-quality evidence on participants developing new cancers was reported in 19 trials (103 events; RR = 0.92; 95% CI, 0.63-1.36).
“Existing weight-loss trials and those in the future need to publish data on long-term clinical outcomes,” Avenell said. “Other types of weight-loss diets (eg, low-carbohydrate, very low-calorie diets) need more evidence from large, well-conducted long-term clinical trials with adequate statistical power to support them. Research is particularly needed on the long-term behavior change techniques that can be used to help people sustain weight loss. However, most research is needed into policies that can change the obesogenic environment to prevent obesity in the first place, and to also support those who have lost weight.” – by Amber Cox
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Alison Avenell, MD, can be reached at firstname.lastname@example.org.
Disclosures: The authors report no relevant financial disclosures.