Clinical Edge

Summaries of Must-Read Clinical Literature, Guidelines, and FDA Actions

Weight Loss Diets & All-Cause Mortality

BMJ; ePub 2017 Nov 14; Ma, Avenell, et al

Among adults with obesity, weight reducing diets with or without exercise advice or programs may reduce premature all-cause mortality, a recent study suggests. The systematic review and meta-analysis of 54 randomized controlled trials (RCTs) included 30,206 participants and examined dietary interventions targeting weight loss, with or without exercise advice or programs, for adults with obesity and followed-up at ≥1 year. The study sought to determine whether weight loss interventions for adults with obesity affect all cause, cardiovascular (CV), cancer, and body weight. Among the findings:

  • High quality evidence found the weight loss interventions decrease all-cause mortality (risk ratio 0.82), with 6 fewer deaths per 1,000 participants.
  • Moderate quality evidence showed an effect on CV mortality (RR, 0.93) and very low-quality evidence showed an effect on cancer mortality (RR, 0.58).
  • 24 trials (15,176 participants) reported high quality evidence on participants developing new CV events and 19 trials (6,330 participants) proved very low-quality evidence on participants developing new cancers.

Citation:

Ma C, Avenell A, Bolland M, et al. Effects of weight loss interventions for adults who are obese on mortality, cardiovascular disease, and cancer: Systematic review and meta-analysis. [Published online ahead of print November 14, 2017]. BMJ. doi:10.1136/bmj.j4849.

Commentary:

We know that there is a strong association between obesity and increased risk of premature mortality, cardiovascular disease, some cancers, type 2 diabetes, and a number of other diseases. There is robust data that lifestyle modification, specifically diet and exercise, decreases the risk of developing type 2 diabetes.1 There has been an open question regarding whether weight loss through diet is beneficial in decreasing the risk of disease and improving age-adjusted mortality. The current study shows that weight loss diets lead to an 18% decrease in premature mortality over a median duration of 2 years. This makes sense and supports efforts to advise patients. The question then becomes which diet to recommend, and the answer is not clear. In fact, there may not be one correct diet, but rather it may vary for different individuals. For patients with hypertension or others at increased cardiovascular risk, a low-salt DASH diet, or the Mediterranean diet make sense. As a general recommendation for weight loss, recent evidence suggests a low-carbohydrate diet may be more effective at achieving weight loss than a low-fat diet.2 While the decision about which diet to use is clearly important, even more important is understanding how significant it is to move forward with some diet, recommending weight loss and exercise to our patients who are overweight and/or sedentary, and utilizing referral to a dietician as an excellent service to our patients. Patients do hear us when we tell them how important it is to take lifestyle modification seriously and when we help them to formulate clear achievable lifestyle goals. —Neil Skolnik, MD

  1. Diabetes Prevention Program Research Group. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med. 2002;346:393-403. doi:10.1056/NEJMoa012512.
  2. Tobias DK, Chen M, Manson JE, Ludwig DS, Willett W, Hu FB. Effect of low-fat diet interventions versus other diet interventions on long- term weight change in adults: A systematic review and meta-analysis. Lancet Diabetes Endocrinol. 2015;3:968-79. doi:10.1016/S2213- 8587(15)00367-8.

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