Is cutting carbs the thing that makes a diet work?

Christopher D. GardnerPhD · nutrition scientist, Stanford Prevention Research Center

No. Once both diets exclude added sugar and refined grain, the carbohydrate level stops deciding the outcome.

What it rests onA 12-month randomised trial in 609 adults where a healthy low-fat and a healthy low-carbohydrate arm produced median weight changes of 5.3 kg and 6.0 kg with no significant difference, and where neither a prespecified genotype pattern nor baseline insulin secretion moderated the effect. A second trial in prediabetes and type 2 diabetes found ketogenic and Mediterranean-plus arms did not differ on HbA1c at 12 weeks. He concedes a small behavioural edge to low-carbohydrate eating (gar-lowcarb-edge) and locates it in cheating patterns rather than metabolism.

Shawn BakerMD · orthopedic surgeon and strength athlete

Yes. Carbohydrate is the one macronutrient you can remove entirely, and removing it is the intervention.

What it rests onMechanistic: gluconeogenesis supplies the glucose red blood cells and liver cells require and ketones can supply most of the brain's energy, so carbohydrate has no dietary requirement while protein and fat do. Operationally he sets a working target under 20 g net carbohydrate a day with fat at roughly 60 to 75 percent of calories (bak-carb-target), while noting ketosis is optional.