High protein diet or high carbohydrate diet, which is better for weight loss?

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By Jimmy Downs

Monday Feb 18, 2013 (foodconsumer.org) -- Many people use a high protein diet, which is in many cases characterized by having low carbohydrates and high meat and or high fat like atkins' diet, to lose weight without knowing the fact this diet can cause a range of serious health conditions including kidney failure, high cholesterol, osteoporosis and kidney stones, cancer, and unhealthy metabolic state (ketosis) among other things, according to webmd.com.

A new study recently published in  the American Journal of Clinical Nutrition suggests that people do not have to risk their life to lose weight by eating a high protein diet.  A diet with high carbohydrates can work equally well if the daily intake of calories is restricted, which is key to weight loss.

Giulio Marchesini MD  from Alma Mater Studiorum University in Italy and colleagues conducted the small trial and found that eating a  high carbohydrate diet for one year had the same effect on weight loss as eating a high protein diet for the same period.

Previous studies yielded inconsistent conclusions on how the ratio of carbohydrates to proteins affects the efficacy of weight loss.  In the current study, the researchers tested a high protein diet and a high carbohydrate diet in 88 obese participants at a mean age of 46.7 years who also received cognitive behavior therapy.

In the trial, all participants were subject to a 3-week inpatient and 48-week outpatient treatment and continuous cognitive behavior therapy throughout the one-year study.  Men used 1500 kcal per day and women used 1200 kcal per day with 20% energy from fat and less than 10% from saturated fat.  The high protein diet had 34% energy from proteins and 46% from carbohydrates while the high carbohydrate diet had 17% from proteins and 64% from carbohydrates.  The primary outcome was weight loss at the end of the one-year study and secondary outcomes were attrition rates and changes in cardiovascular factors and psychological profile, according to the trial report.

The researchers found the efficacy of weight loss and attrition rates in both groups were similar.  Attrition rates were found at 25.6% in both groups while weight loss was on average by 15% in those on the high protein diet and 13.3% in those on the high carbohydrate diet at the end of one year of intervention.  There is no significant difference in weight loss in both groups.  Both diets improved secondary outcomes to a similar degree.

The researchers concluded "The relative carbohydrate and protein content of the diet, when combined with intensive CBT (cognitive behaviour therapy), does not significantly affect attrition rate, weight loss and psychosocial outcome in patients with severe obesity."

A high protein diet can stress the kidney, which is why it can lead to kidney failure when the diet is used for a long term.    According to China Study, a book authored by Dr. T Colin Campbell, a Cornell University nutritionist, Americans on average use a diet with about 17% energy from proteins, which is excessive according to Dr. Campbell.  In that book, Dr. Campbell suggests that normally no more than 11% energy should come from proteins.

When it comes to weight loss, Dr. Campbell says in his book that a plant-based diet is key.  He says that the Chinese in the rural areas in China eat lots of carbohydrates but little meat never have to worry about weight gain nor have to lose weight even though they eat more calories than Americans.

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