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Low-Carb Diets Beat Low-Fat for Weight Loss And Lipid Changes at 2 Years

Both a low-carbohydrate diet or a Mediterranean-style diet may be " effective

alternatives " to a low-fat diet, with more favorable effects on lipids and

glycemic control, published in last weeks� New England Journal of Medicine.�

The two-year study, which managed to keep almost 85% of the 322 study

participants on one of the three diets for the entire period, offers the hope

that

weight-loss diets can be tailored to personal preferences, without sacrificing

efficacy, researchers say.

Dr Iris Shai

lead author on the study (Ben Gurion University of the Negev, Beer-Sheva,

Israel) stated that, " Several recent one-year dietary studies have led the

American Diabetes Association

to state in January 2008 that low-carb diets should be considered for a maximum

of one year. " � " The current two-year study suggests that one low-fat diet

doesn't fit all, meaning that the old paradigm should be reconsidered. "

At the start of the study, DIRECT subjects were middle-aged (mean age 52 years)

and mildly obese (body-mass index = 31). All participants were randomized

to one of three diets: low-fat/restricted-calorie diet;

Mediterranean/restricted-calorie diet; or low-carbohydrate diet, with no

restriction on calories.

After two years, adherence to their respective diets ranged from more than 90%

in the low-fat group, to 85% in the Mediterranean diet group, to 78.0% in

the low-carb group.

Weight loss occurred in all three groups over the 24 months but was greater in

the Mediterranean and low-carb groups. In men � who made up the bulk of the

study cohort � weight loss was greatest in the low-carb group, whereas women

� just 45 in the study cohort � appeared to lose more weight on the

Mediterranean

diet. When the analysis was performed just in the 272 " completers " who adhered

to the diet for the entire study period, the pattern of weight loss associated

with each diet was similar.

Weight loss

Changes in lipid parameters were also most striking in the low-carb and

Mediterranean-diet groups. High-density lipoprotein (HDL) increases and

triglyceride

decreases were most pronounced in the low-carb group, while reductions in

low-density lipoprotein (LDL) cholesterol were greatest in the

Mediterranean-diet

group. Reductions in total cholesterol/HDL ratio were greatest in the low-carb

group, closely followed by the Mediterranean-diet group.

Lipid changes

In the subset of patients with diabetes � just 36 out of 322 subjects � the

Mediterranean diet appeared to improve fasting plasma glucose levels. According

to Shai, the results suggest that " one size doesn't fit all. "

" The current results suggest that Mediterranean and low-carbohydrate diets are

effective alternatives to low-fat diets, " she said. " The more favorable effects

on lipids with the low-carbohydrate diet and on glycemic control with the

Mediterranean diet suggest that personal preferences and metabolic

considerations

might inform individualized tailoring of dietary interventions. "

One of the unique features of the study was its location: the DIRECT study was

conducted at a nuclear research center in Israel with an on-site cafeteria

and medical clinic. Participants in the trial ate their main meal of the day �

lunch � in the workplace cafeteria, where food choices were carefully

controlled

and labeled. On-site dieticians worked regularly with participants to help them

adhere to their diets. Indeed, the Nuclear Research Center Negev itself,

along with the

C and Atkins Foundation

� the low-carb diet in DIRECT was based on the Atkins diet � helped fund the

study.

In the paper, Shai et al acknowledge that the setting was perfectly suited to a

study of this kind, but that this doesn't mean these diets would not have

worked elsewhere. " We took advantage of the isolated place, which is highly

monitored by an excellent internal medical department, and a set of cafeterias

[whose menus] we could modify. And in fact, she said, " we do believe that this

optimal model could be applied in other workplaces, once the manager prioritizes

this kind of long-term health-promotion project. "

Low-carbohydrate diets have been compared with low-fat diets and thought to be

feasible for weight loss, whereas a Mediterranean diet with moderate fat

and high fiber and fish provides cardiovascular benefits, but common problems of

weight-loss programs include high attrition rates and short duration.

This is a randomized trial conducted at a workplace with a medical clinic for 24

months in patients aged 40 to 65 years to compare the effect of the 3 diets

on weight loss and metabolic changes.

Practice Pearls:

Use of a low-fat, Mediterranean, and low-carbohydrate diet for 24 months is

associated with weight loss in men and women.

Use of a low-fat, Mediterranean, and low-carbohydrate diet for 24 months is

associated with reduced waist circumference, improved lipid profile (best for

low-carbohydrate diet), improved glycemic control (Mediterranean diet), and

improved blood pressure.

Shai and colleagues publish the results of the

Dietary Intervention Randomized Controlled Trial

(DIRECT) in the July 17, 2008 issue of the

New England Journal of Medicine L

Shai I, Schwarzfuchs D, Henkin Y, et al. Weight loss with a low-carbohydrate,

Mediterranean, or low-fat diet.