Low-carbohydrate diet effective for reducing weight, BP

A low-carbohydrate, ketogenic diet appears to be equally effective for reducing weight compared with the weight-loss drug orlistat in combination with a low-fat diet, but may be more effective in reducing BP, according to new study findings.

Researchers enrolled 146 participants with similar intake of calories, macronutrients and fiber in the study. Participants assigned to the low-carbohydrate, ketogenic diet (n=57) were instructed to restrict carbohydrate intake to <20 g per day; those assigned to combination orlistat plus a low-fat diet (n=65) were instructed to restrict their consumption of total fat (<30% of daily energy), saturated fat (<10% of daily energy), cholesterol (<300 mg daily) and calories in addition to 120 mg oral orlistat three times per day (Xenical, Roche; Alli, GlaxoSmithKline).

Weight loss during the 48-week study was comparable between the two groups. Low-carbohydrate diet participants experienced a mean change from baseline of 11.4 kg (–9.5%) compared with 9.6 kg (–8.5%) for the low-fat diet/orlistat participants.

However, participants assigned to the low-carbohydrate diet had greater reductions in systolic (–5.9 mm Hg) and diastolic BP (–4.5 mm Hg) compared with participants assigned to a low-fat diet/orlistat (1.5 mm Hg and 0.4 mm Hg).

“I expected the weight loss to be considerable with both therapies, but we were surprised to see BP improve so much more with the low-carbohydrate diet than with orlistat,” William S. Yancy Jr., MD, associate professor of medicine at Duke University, said in a press release. “While weight loss typically includes improvements in BP, it may be that the low-carbohydrate diet has an additional effect.”

Improvements in HDL, triglycerides and waist circumference were also similar between the two groups.

“It is clear now that several diet options can work, so people can be given a choice of different ways to lose weight,” Yancy added. “But more importantly, we need to find new ways to help people maintain their new lifestyle.”

Yancy WS. Arch Intern Med. 2010;170:136-145.

The paper by Yancy and colleagues is not surprising. While the low carbohydrate/ketogenic diet has come under much criticism through the years, it works for weight loss, as do all other diets, except this one is a bit faster to drop the weight. We showed more than a decade ago that use of orlistat (Xenical; Roche; Alli, GlaxoSmithKline) results in weight loss and BP reduction. Others have shown this with the low-carbohydrate diet as well. It is the weight loss not the diet that provide this result. This is not the point - all diets work if they are followed properly; the key is to sustain the weight loss. All long-term studies demonstrate that weight loss can be maintained for six to nine months, but after one year there is regression to the mean. The current study was 48 weeks.

The easiest concept to remember for weight loss is 'it's all about the calories.' People should save money — not calories. So buy less and eat about 50% of the current portion size that you are currently eating and you will lose weight and keep it off. The current culture in the United States doesn't reinforce weight loss. People are working longer hours and eating healthy is more expensive than the alternative. The food industry needs to partner with the dietitians and physicians through a nationwide effort to ameliorate this burden. It is doable but will take a commitment on the part of the food industry and the government.

– George Bakris, MD
Cardiology Today Editorial Board