Science Has Spoken: All Popular Weight-loss Diets Are the Same

By Kam Kompani,

April 14, 2020

A new scientific review has in all likelihood provided a decisive answer to the health and fitness industry’s million-dollar question: Out of all the popular diets out there, which one is the best? It turns out they’re all pretty much the same.

The study, which is the biggest systematic review to test popular diets, looked at over 121 randomised trials, with a combined total of 21,942 patients.

In total, 14 brand-name diets were tested: Low carbohydrate diets (such as Atkins, South Beach, and Zone), “moderate” diets with a balanced macronutrient profile (such and Biggest Loser, DASH Mediterranean, Slimming World, and Weight watchers), and low fat diets (Ornish and Rosemary Conley).

All 14 diets led to weight loss and lower blood pressure during the first 12 months. But their effectiveness started to diminish quickly.

Patients began to lose weight at a slower pace after just 6 months, before any losses became negligible past the 12-month mark.

Similarly, the cardiovascular benefits of all 14 diets, except the Mediterranean diet, “essentially disappeared” after 12 months, the researchers observed.

The improvements in blood pressure and blood lipids were also found to come to a halt after the first year.

If you really had to pick one of the 14 diets, Jenny Craig and Atkins proved to be the most effective, while the Biggest Loser and Slimming World scored the worst.



The worldwide prevalence of obesity nearly tripled between 1975 and 2018.

While discussing their study’s limitations, the authors acknowledged that most of the participants were not asked to report whether they had truly stuck to their diet, which is not necessarily a “limitation”, as it could have made their results more applicable to real-world situations.

“Adherence to diets was generally not reported, and could have been low, particularly at 12 months. If this is the case, our results describe what is likely to happen for average adherence by patients,” the authors noted.

Based on their findings, the researchers concluded that: “Differences between diets are generally trivial to small, implying that people can choose the diet they prefer from among many of the available diets without concern about the magnitude of benefits.”

Compared With Other Studies

The authors pointed out that their paper had nearly three times the number of participants compared with previous reviews. Their observations are also in line with their own past research and some of the latest dietary guidelines.

“Our findings are also consistent with the 2014 joint guidelines from the American Heart Association, the American College of Cardiology, and The Obesity Society, concluding that evidence was inadequate to recommend any particular diet,” the researchers said.

Adding that: “For reduction of cardiovascular risk, recent dietary guidelines from the US and Canada, and the EAT Lancet commission have recommended plant-based diets.”



Study: Long Ge et al. (2020). “Comparison of dietary macronutrient patterns of 14 popular named dietary programmes for weight and cardiovascular risk factor reduction in adults: systematic review and network meta-analysis of randomised trials”. BMJ 2020; 369.