Eating style
Atkins
A phased low-carb plan that starts near keto levels and adds carbohydrate back in steps. How it differs from keto and what the trials found.
How the phases work
Atkins has four phases. Phase 1 allows about 20 g of net carbs a day, mostly from non-starchy vegetables, for at least two weeks. Phase 2 adds back nuts, seeds and berries while weight keeps falling. Phase 3 adds roughly 10 g of carbohydrate a week, pulling back if weight loss stops, until you reach your goal weight. Phase 4 is the level you then hold for good.
Net carbs means total carbohydrate minus fibre. Our recipes show carbohydrate and fibre separately, so you can subtract one from the other. Protein and fat are not capped, which is why Atkins meals lean on meat, fish, eggs, cheese and oils alongside the vegetables.
How it differs from keto
Keto is defined by staying low enough in carbohydrate, usually under 50 g a day, to remain in ketosis. Atkins only starts there. Its later phases deliberately raise carbohydrate, so most people finish on a moderate low-carb diet. Our low-carb and keto guide explains the very-low end, which is what phase 1 amounts to, and who should be careful with it.
What the trials found
In a 2020 network meta-analysis of 121 trials, Atkins produced about 5.5 kg more weight loss than a usual diet at six months, the most of the named diets, with a fall in blood pressure. By 12 months the weight loss had shrunk and most of the improvement in risk markers had gone, as it had for nearly every diet studied.
A 2022 Cochrane review of 61 trials found low-carbohydrate diets led to about 1 kg more weight loss than balanced-carbohydrate diets over up to two years, a difference it judged to be little to none. An earlier meta-analysis of 48 trials likewise found that differences between named diets were small. Atkins works about as well as any diet you can keep to.
Worth knowing
- If you take insulin, other diabetes medication or diuretics, speak to your clinician before starting: doses may need to change. It is not suitable for people with severe kidney disease.
- Headache, dizziness, tiredness and constipation are common in the first phase. Keeping the vegetables in helps with fibre.
- Low-carbohydrate diets lower LDL cholesterol less than low-fat diets do. If your cholesterol is raised, ask for it to be rechecked after a few months.
Common questions
Do I have to buy Atkins-branded products?
No. The phases are defined by grams of carbohydrate, not by products. Ordinary meat, fish, eggs, vegetables, nuts and dairy cover every phase.
Is Atkins better than keto for weight loss?
There is no good head-to-head evidence. Both restrict carbohydrate, and reviews find that low-carb diets as a group lose about the same weight as other diets over one to two years.
Sources
- Mayo Clinic: Atkins Diet, what’s behind the claims?
- Ge et al., BMJ (2020): Comparison of 14 popular named dietary programmes, systematic review and network meta-analysis
- Naude et al., Cochrane Database of Systematic Reviews (2022): Low-carbohydrate versus balanced-carbohydrate diets for reducing weight and cardiovascular risk
- Johnston et al., JAMA (2014): Comparison of weight loss among named diet programs, a meta-analysis
General information, not medical or dietary advice. Speak to a doctor or registered dietitian about your own situation.
