Mostly true: “The best diet is the one you can stick to.”

Mostly true

Evidence confidence Moderate

The short answer

For weight loss, the diet you can keep up matters much more than its mix of carbs, fat and protein.

What this means for you

For weight loss, choose the eating pattern that makes it easiest for you to eat a bit less and keep doing it, whether that means fewer carbs, less fat or another approach. A diet you stick to still has to lower how much you eat: eating only healthy foods does not make calories stop counting, which is why our card on that claim rates it false. Expect modest results and plan for how you will keep the weight off after the first months.

Your next step

Pick one way of eating you could see yourself following a year from now, and judge it by whether you can keep eating less on it, not by its carb or fat rules.

Who should be careful?

Safety note: Cutting carbs sharply while taking insulin or other blood-sugar-lowering medicines can cause low blood sugar, so doses may need to be lowered from the start. Diabetes experts have not found enough evidence to recommend very low-carb eating during pregnancy or for people with chronic kidney disease or disordered eating.

Talk to a healthcare professional if: you take insulin or other diabetes medicine, have kidney disease, are pregnant, have a history of an eating disorder, or plan a very restrictive diet.

Why this confidence?

Large randomized trials and tightly controlled feeding studies find that diets with very different amounts of carbs and fat give similar weight loss when people eat similar amounts, and that how closely people stick with a diet tracks how much they lose. It is mostly true, with moderate confidence, because the losses were modest and partly regained, and the link between sticking with a diet and results comes from comparing people within trials rather than from testing it directly.

The facts

For weight loss, the diet you can keep up matters much more than its mix of carbs, fat and protein. Diets work by helping you eat fewer calories than you burn, and when people eat similar amounts, diets with very different carbs and fats lead to similar weight loss.

The bigger picture

In a 2-year trial of 811 adults on four reduced-calorie diets with different amounts of fat, protein and carbs, everyone lost about 13 pounds on average by 6 months, started to regain after a year, and ended with similar losses of about 6.6 to 7.9 pounds; people who came to more group sessions lost more. In a 12-month trial of 609 adults, healthy low-fat and healthy low-carb diets gave similar weight loss (11.7 vs 13.2 pounds), and neither gene tests nor insulin tests predicted who would do better on which diet. In a review of 32 feeding studies where calories were kept equal, swapping carbs for fat made only tiny differences in fat loss, and the small edge went to the lower-fat diets, not low-carb.

Sticking With It

In a 1-year trial of 160 adults assigned to Atkins, Zone, Weight Watchers or Ornish, each diet led to a similar, modest loss of about 4.4 to 6.6 pounds on average. How closely people said they stuck with their diet was strongly linked to how much they lost, while which diet they were on was not. Only 50 to 65 percent of people in each group finished the year.

Sources (5)

“The best diet is the one you can stick to.”

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