Many claims in lay media and
scientific literature have been made regarding the superiority of a certain diet
for inducing weight loss. Two recent studies
one published in the Journal of the American
Medical Association and the second in Annals
of Internal Medicine found that using either a low-carbohydrate or low-fat diet had the same end result. The best diet
is that which works best for the dieter.
Johnston et al report in JAMA finding
from their search of 6 electronic databases based on which they estimated the
relative effectiveness of diets to affect weight and body mass index from
baseline. Weight loss and body mass
index was determined at 6- and 12-month follow-up.
Among 59 eligible articles reporting
48 unique randomized trials that included 7286 individuals, the largest weight
loss was associated with low-carbohydrate diets 8.73 kg at 6-month follow-up
and 7.25 kg at 12-month follow-up and low-fat diets 7.99 kg at 6-month
follow-up and 7.27 kg at 12-month follow-up. Weight loss differences between
individual diets were minimal. For example, the Atkins diet resulted in a 1.71
kg greater weight loss than the Zone diet at 6-month follow-up.
They concluded significant weight
loss was observed with both low-carbohydrate or low-fat diet. Weight loss
differences between individual named diets were small.
In the
study by Bazzano et al published by the Annals of Internal Medicine, the effects
of a low-carbohydrate diet compared with a low-fat diet of on body weight and
cardiovascular risk factors was determined.
148 men and women without
clinical cardiovascular disease and diabetes were placed on a low-carbohydrate
(<40 g/d) or low-fat (<30% of daily energy intake from total fat [<7%
saturated fat]) diet.
Data on weight, cardiovascular
risk factors, and dietary composition were collected at 0, 3, 6, and 12 months.
Sixty participants (82%) in the
low-fat group and 59 (79%) in the low-carbohydrate group completed the
intervention. At 12 months, participants on the low-carbohydrate diet had
greater decreases in weight (mean difference in change, −3.5 kg), fat mass
(mean difference in change, −1.5%), ratio of total–high-density lipoprotein
(HDL) cholesterol (mean difference in change, −0.44), and triglyceride level
(mean difference in change, −0.16 mmol/L) and greater increases in HDL
cholesterol level (mean difference in change, 0.18 mmol/L) than those on the
low-fat diet.
They concluded low-carbohydrate
diet was more effective for weight loss and cardiovascular risk factor
reduction than the low-fat diet.
Based on these studies both
low-carb and low-fat diets induced weight
loss but there was not a sizable differences between the two. Finally, the
branding of the diet did not have an impact on weight loss.
