Low-Carb Diet Linked to Greater Weight Loss Than Low-Fat Diet — Physician’s First Watch

Medical News |
September 2, 2014

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

By Kelly Young

Edited by David G. Fairchild, MD, MPH, and Jaye Elizabeth Hefner, MD

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."

Reader Comments (13)

H ROBERT SILVESTEIN Physician, Cardiology, Preventive Medicine Center

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, 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) & are usually not just based on berries, cooked vegetables/vegetables soups/beans (beans as 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 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, FACC

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Am I missing something? The low carb group ended up eating almost as many carbs as the low fat group by the end of the study. The diets should be called: low fat versus high fat to be accurate. Also compare the results of this study with a tiny population ( 20% drop outs) with JAMA's review of over 7000 subjects on low carb or low fat diets. NO DIFFERENCE in weight outcomes. Shows how much damage some PR can do in obscuring facts.

Dan d P T Other Healthcare Professional, Cardiology

None at this time. Interested in follow up comments

MARGARET HARDY Physician, Family Medicine/General Practice, australia

Prof Stephen Simpson at Sydney University has recently published results of mice experiments: low carb, high protein diet resulted in poorer cardiometabolic outcomes and shorter lifespans than a high carb, low protein diet (but slightly higher bodyweight on the latter). The high fat low protein diet had the worst outcomes. Essentially reducing calorie intake below output will result in weight loss whatever form of diet you undertake, but we must be cognizant of nutirional value and longterm outcomes for our patients.

Dora Mendoza, MD,PhD,MSC,MPH Other, Endocrinology, Bogotá,Colombia, S.A

The diets that are more frecuently use to loose weight:
Nathan Pritikin, Robert Atkins, Michael and Mary Eades, are all
good and dependent of the person who eat them: normal blood lipids, normal uric acid, they can use any of them. All of these diets do not mix carbohydrates, proteins and fat (the animals do not mix these products and they are no obese or they do not get sick.)

Vincent Maieli Retired

Am I missing something???? Comparing a LOW FAT diet as < 30% (Average diet 2000 cal * 30% = 660 calories with a LOW CARB diet of <40Grams=160 calories. certanily, since the LOW CARB diet has fewer calories, this would result in a greater weight loss. Please explain???

Scott A Joseph, MD Physician, Psychiatry, Inpatient State Hospital

Well, it should be pointed out that the ultimate low fat diet is cotton candy, and the ultimate low carb diet is steak. Note that candy manufacturers actually advertise their products as being "low fat."

Eduardo Mazzi

Sello me caras
Bye fats

Ellen Grant MBChB, DObstRCOG Physician, Neurology, Retired

There is nothing new about the Stone Age diet which is claimed to be described by Hippocrates and is used by doctors practising Ecological Medicine (or Clinical Ecology). In the UK one of the pioneers was Dr Richard Mackarness who wrote the book, “Eat Fat and Grow Slim” in 1958. Another was Dr John Mansfield who described a lamb and pears diet to identify masked food allergens which caused a range of symptoms including weight gain. Wheat and corn were the commonest of the food allergens unmasked and avoiding these and other headache precipitants resulted in 85% of patients becoming headache free with reductions in weight and blood pressure and headache medications reduced.1

1 Grant ECG. Food allergies and migraine. Lancet 1979; 1:966-69.

Peter Ostrow MD, PhD Physician, Pathology, University at Buffao School of Medicine

The caloric intake of participants in the two groups was said to be similar, but the low-carb group reported an average intake of 1448 calories at 12 months (table 2), which is 79 calories per day less than the low-fat group. over the 365 days of the study, that totals 28,835 calories. At 3,500 calories/lb, that equals 8.24 lb, slightly more than the entire difference in weight loss between the two groups. This extra weight loss might also have been responsible for some of the other differences in risk factor between the groups. There is a message here for dieters: if you cut back a small number of calories every day, you will lose a substantial amount of weight in a year.

M Griffin, MD, MBA Physician, Emergency Medicine

I am not part of this study, so the comment is on diets in general.One of the key elements of the low fat diets: you are hungry again very quickly and likely to eat more/more often. This seems to be due to rapid rise and fall in insulin levels, as the fat in the food is replaced with sugar and sodium to make it taste decent.
The low carb diets typically replace the calories with food that has more sustained release of calories, low glycemic index, so you are satisfied longer, so tend to eat less, and have fewer total calories when you count at the end of the day. So your point about the low carb dieters eating less may actually be pointing to one of the main reasons these low carb diets work better.

Eileen Mullard MSc, BSN, RN,RGN, PGCLTHE,BCMA Other Healthcare Professional, Oncology

Are the diet booklets available online with the low carb suggestions? I would like to share this with some colleagues. Thanks

AMY HERMAN Editor, Physician's First Watch

Unfortunately, the authors do not provide any way to access the handbooks used in this study.

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