In this article
Editorial update: September 29, 2026. Text prepared with AI support from the indicated sources. No independent clinical review. General information, not an individual meal plan.
Short answer
The ketogenic diet is the most restrictive form of low carb: it is normally below 50 g of carbohydrates per day, while Diabetes UK defines low carb as less than 130 g. For weight loss, the studies cited here do not show a clear long-term winner, so the best choice tends to be the one you can maintain with guidance.
What is low carb
For Diabetes UK, eating low carb means reducing carbohydrates to less than 130 g per day.
What is the ketogenic diet
The ketogenic diet normally reduces carbohydrates to less than 50 g per day, possibly as low as 20 g. With so little carbohydrate, the body first uses the glucose stored in the liver; if this continues for 3 to 4 days and the store runs out, insulin falls and fat becomes the main fuel, with the liver producing ketone bodies. The full explanation is in what is the ketogenic diet.
Side-by-side differences
| Aspect | Low carb | Ketogenic |
|---|---|---|
| Carbohydrates per day | Less than 130 g (Diabetes UK) | Normally less than 50 g, sometimes 20 g (Harvard) |
| Goal | Reduce carbohydrates | Reduce them enough for the body to produce ketone bodies |
| Restriction | Lower | Higher: cuts grains, starchy tubers, legumes and most fruits |
Which loses more weight?
The Cochrane review, with 61 trials in adults with overweight or obesity, concluded that low carb diets probably result in little or certainly result in little or no difference in weight loss compared to balanced carbohydrate diets, between 3 and 8.5 months and between 1 and 2 years. Diabetes UK also says there is no consistent evidence that low carb is more effective than other approaches long term for people with type 2 diabetes.
For keto in particular, Harvard points to short-term benefits in some people, but after a year, the effects are not significantly different from those of conventional weight-loss diets. None of the sources compares keto and low carb directly: Cochrane compares low carb (including very low, up to 50 g) with balanced diets, and Harvard compares keto with conventional diets. The details are in does the ketogenic diet really make you lose weight?.
And for those with diabetes?
Diabetes UK considers low carb diets of 50 to 130 g of carbohydrates per day an effective short-term option for adults with type 2 diabetes and overweight or obesity, but does not recommend them for type 1 diabetes. And those with type 2 diabetes who use SGLT2 inhibitors, such as dapagliflozin or canagliflozin, should talk first with the health team, because reducing carbohydrates can increase the risk of diabetic ketoacidosis. Those who use insulin or another diabetes medication that can cause hypoglycemia also need to talk with the team first: low carb can increase this risk, and the medication may need to be adjusted.
How to choose
Talk with a doctor and dietitian before starting either of the two, especially if you have any condition, take medication, are pregnant or breastfeeding: there are still doubts about the safety of keto in kidney and liver disease and in pregnancy, breastfeeding, childhood and adolescence. If the choice is ketogenic, the step by step to get started and the 7-day meal plan help in practice.
Sources
- Diabetes UK: Low-carb diet and meal plan
- Diabetes UK: Low-carb diets position statement for professionals (May 2021)
- Harvard T.H. Chan School of Public Health, The Nutrition Source: Diet Review: Ketogenic Diet for Weight Loss
- Cochrane: low carbohydrate diets or balanced carbohydrate diets for weight loss and cardiovascular risk
Mariana is passionate about a healthy lifestyle.
