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CardioExchange, an NEJM practice community for medical professionals dedicated to improving cardiac patient care, was active from 2009 to 2015. CardioExchange fostered discussion between clinicians from across the globe.

September 2nd, 2014

Low-Carb Diet Linked to Greater Weight Loss Than Low-Fat Diet

A low-carbohydrate diet is associated with greater weight reduction than a low-fat diet among obese adults, according to an Annals of Internal Medicine study.

Roughly 150 obese adults who were otherwise healthy were randomized to eat either a low-fat (<30% fat) or low-carbohydrate (<40 g/day of digestible carbohydrates) diet. Participants were provided diet-specific handbooks with recipes and meal-planning tips in addition to a daily meal-replacement shake or bar.

At 12 months, the low-carb group had lost 3.5 kilograms more than the low-fat group, even though caloric intakes were similar. The low-carb group also saw greater improvements in body composition, CRP levels, HDL cholesterol, and triglycerides.

NEJM Journal Watch Cardiology editor-in-chief Harlan Krumholz comments: “This study, a welcome trial in an area where we need them, supports the new conventional wisdom that low carb is better than low fat for losing weight — what we do not yet know is which diet is better for lowering risk. That information will require larger trials with much longer follow-up — but we desperately need that information.”

Background: NEJM Journal Watch Cardiology summary on long-term consequences of low-carb diet

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2 Responses to “Low-Carb Diet Linked to Greater Weight Loss Than Low-Fat Diet”

  1. Uffe Ravnskov, MD, PhD says:
    September 6, 2014 at 5:19 am

    Judged from the participants´ mean insulin level at baseline, many of them must have suffered from the metabolic syndrome. A relevant question is therefore if the result would have been even better if the authors had excluded patients with normal insulin sensitivity. For instance, in a dietary trial by Volek et al. including only patients with the metabolic syndrome, the patients had lost on average 10 % of their body weight already after 12 weeks treatment (1).

    The explanation why the result in many dietary trials is less impressive may be because they have included both insulin-sensitive and insulin-resistant patients, and there is evidence that a lowcarb diet is less effective for insulin-sensitive people. As support for that view is a dietary trial by Cornier et al. They found that weight loss in obese insulin-sensitive women was greater on a high-carb diet, whereas women with insulin-resistance lost more on a lowcarb diet (2).

    1. Volek JS et al. Carbohydrate restriction has a more favorable impact on the metabolic syndrome than a low fat diet. Lipids. 2009 Apr;44(4):297-309
    2. Cornier MA et al. Insulin sensitivity determines the effectiveness of dietary macronutrient composition on weight loss in obese women. Obes Res. 2005 Apr;13(4):703-9.

  2. H Robert Silverstein, MD says:
    September 6, 2014 at 3:07 pm

    my, my, my: UR, MD, above is rather profound. David Katz, MD, does super analysis of this faulty study today on MedPage. My 2 cents? Here ’tis.

    The Law Of Probability. “If you do things right, most of the time they turn out right but occasionally they will turn out wrong. If you do things wrong, most of the time they will turn out wrong, but occasionally they will turn out right.” Such is the case here: done wrong, turns out right. Consider both primary & secondary goals: higher protein diets are more satisfying but biologically incorrect for humans if you ask a comparative anatomist: this has implications for osteoporosis, adverse changes in gut microbiota, kidney stones, increased production of dangerous cytokines. On the other hand, high carbohydrate diets are less tasty/filling and usually contain refined carbs (which everyone knows are a no-no) & usually are not just based on berries, cooked vegetables (excluding the potato family)/vegetables soups/beans (beans as perfect protein)-which is biologically correct for the human biology. As long as drugs are not used, I have no objection to what method of weight loss is used(even including 1-2 days a week of water or juice fasting) as overweight itself is a prime mover for so many diseases. In time, the high animal protein diets can/should transition to a more biologically correct (ideally organic) unprocessed whole foods diet that focuses primarily on very filling low temp-cooked vegetables/vegetable soups (plus limited amounts of other ideal carbs) in order to maintain both health and weight loss. HRS, MD, FAC