CV benefits, weight loss similar among most popular diets at 6 months
Most macronutrient weight loss diets led to substantial improvements in CV risk factors and modest weight loss over months, according to a systematic review and network meta-analysis published in The BMJ.
At 12 months, weight loss diminished among all popular-named diets and macronutrient patterns and the benefits for CV risk factors for most interventions disappeared, according to the study.
“Differences between diets are, however, generally trivial to small, implying that people can choose the diet they prefer from among many of the available diets without concern about the magnitude of benefits,” Long Ge, PhD, researcher at the Evidence-Based Social Science Research Centre at Lanzhou University in China, and colleagues wrote.
Trials assessing different diets
Researchers analyzed data from 21,942 patients who were overweight or obese from 121 trials. Trials included in the meta-analysis reported changes in lipid profile, weight loss, C-reactive protein levels and BP at 3-month follow-up or longer.
The following diets were included in this study:
- low carbohydrate: Atkins, South Beach, Zone;
- moderate macronutrients: Biggest Loser, Dietary Approaches to Stop Hypertension (DASH), Jenny Craig, Mediterranean, Portfolio, Slimming World, Volumetrics, Weight Watchers; and
- low fat: Ornish, Rosemary Conley.
Outcomes of interest were weight loss and related markets of CVD risk, which included systolic and diastolic BP, CRP, LDL and HDL, at 6 and 12 months.
At 6 months, a low-carbohydrate diet had similar effects on weight loss (4.63 kg; 95% credible interval [CI], 3.42-5.87) and reductions in systolic (5.14 mm Hg; 95% CI, 3.01-7.32) and diastolic BP (3.21 mm Hg; 95% CI, 1.89-4.53) compared with a usual diet. This was also observed in low-fat diets with regard to weight loss (4.37 kg) and reductions in systolic (5.05 mm Hg) and diastolic BP (2.85 mm Hg). Slightly less weight loss and BP reductions were observed in moderate macronutrient diets.
Low carbohydrate diets had less of an effect on LDL (1.01 mg/dL) compared with low-fat (7.08 mg/dL) and moderate macronutrient diets (5.22 mg/dL), although it was found to increase HDL (2.31 mg/dL). Moderate macronutrient diets did not have this effect on HDL (0.89 mg/dL).
Compared with usual diet, the largest effect on weight reduction and BP at 6 months occurred with DASH (3.6 kg; 4.7 mm Hg systolic; 2.9 mm Hg diastolic), Atkins (5.5 kg; 5.1 mm Hg systolic; 3.3 mm Hg diastolic) and Zone (4.1 kg; 3.5 mm Hg systolic; 2.3 mm Hg diastolic). No diets in this study improved HDL or CRP levels at 6 months.
At 12 months, weight lost diminished for all popular-named diets and macronutrient patterns. CV risk factor benefit for all interventions were no longer observed except for the Mediterranean diet.
More effective health promotion
In a related editorial, Helen Truby, PhD, professor of nutrition dietetics and food at Monash University in Melbourne, Australia, and Terry P. Haines, PhD, professor in the School of Primary and Allied Health Care at Monash University, wrote: “Persuading the public to adopt eating patterns consistent with dietary guidelines remains problematic. If we are to change the weight trajectory of whole populations, we might learn more from understanding how commercial diet companies engage and retain their customers, and translate that knowledge into more effective health promotion campaigns.” – by Darlene Dobkowski
Disclosures: Ge, Haines and Truby report no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.