WCM-Q team examines the effectiveness of diets for losing weight

Researchers at Weill Cornell Medicine – Qatar (WCM-Q) have conducted a systematic review of diets to attempt to ascertain which is the most effective for reducing obesity in the Middle East and North Africa (MENA) region.

The MENA region has one of the highest prevalence of obesity and associated diseases – including type 2 diabetes – in the world. Very little is known, however, about the effectiveness of dietary regimes in the region and how their efficacy may differ from the same diets in the West.

Led by Dr. Shahrad Taheri, professor of medicine at WCM-Q, the team - Drs. Hadeel Zaghloul, Hadya Elshakh, Abdullah Elzafarany, Odette Chagoury, and Barbara McGowan - reviewed 29 randomized clinical trials of a variety of diets, which included 2,792 adults from five countries in the MENA region. The study participants were generally middle-aged women who achieved average weight changes ranging between -0.7kg (weight gain) and 16kg (weight loss), with the average weight loss being 4.8kg.

Dr. Taheri said: The vast majority of randomized clinical trials of diets have included mainly Western cohorts but there may be social, cultural or physiological reasons which affect diet efficacy when translated to an Arab cohort in Middle Eastern countries.

“With obesity, diabetes, heart disease and stroke having such a devastating impact upon the countries of the MENA region, it would be very useful for healthcare professionals to know which diet is most likely to result in weight loss, or which diet would be the best choice for controlling blood sugar levels in diabetes.”

However, Dr. Taheri said that of the 29 randomized clinical trials available, there was a general lack of information about the weight loss interventions, and variations between the studies meant they could not be accurately compared for efficacy, with the researchers noting that high-quality studies are needed in the MENA region to support clinical practice with evidence-based interventions for obesity.

But there were also some positive findings. One two-year trial involved 322 people who were randomly assigned to one of three diets: low-fat (energy intake limited to 1500 kcal per day for women and 1800 kcal per day for men); Mediterranean, energy restricted; or low-carbohydrate, energy unrestricted. Among the 272 participants who stuck to the diet, the mean weight loss was 3.3 kg for the low-fat; 4.6 kg for the Mediterranean, energy-restricted; and 5.5 kg for the low-carbohydrate, energy unrestricted. There were also positive effects on blood lipids with the low-carbohydrate diet, and on blood glucose levels with the Mediterranean diet.

Dr. Taheri said: “There is an obvious need for more large randomized clinical trials of dietary interventions to be held in the MENA region, and for those trials to involve a wider range of participants, particularly men and young people. In Qatar, we recently conducted the first such clinical trial in the region with participants achieving about 12kg weight loss and 60% of them reversing their type 2 diabetes.

“Despite the need for more research, generally, there is good evidence that increasing consumption of fruit and vegetables while reducing consumption of high-fat, high-sugar, processed food will have positive affects for the vast majority of the population. If you are overweight, then adopting a healthy diet and losing weight are probably the single-most important actions that people can take if they wish to avoid diabetes, heart disease, stroke, some cancers and a host of other non-communicable diseases, although it is always wise to consult your doctor first.”

The full study can be read at https://onlinelibrary.wiley.com/doi/pdfdirect/10.1111/cob.12434.