The 5:2 diet — eat normally for 5 days, restrict to 500 calories on 2 days — popularised by Dr Michael Mosley in the UK. Combined with keto, it becomes an even more potent fat-loss tool.
On your 5 normal keto days, you eat your standard ketogenic diet. On your 2 restricted days, you consume approximately 500 calories (600 for men) from low-carb, high-protein sources. This combination keeps you in deep ketosis even on the 500-calorie days.
Non-consecutive fast days work best. Tuesday and Thursday is a popular combination. Avoid fasting on your most demanding exercise days.
Focus on protein to preserve muscle: 2 eggs (140 cal), a large chicken and vegetable soup (200 cal), and a small portion of Greek yoghurt (100 cal) = 440 calories. Keep carbs under 10g. Explore our low-calorie keto lunch soups and light keto protein mains for fast-day meal ideas.
Most people find keto 5:2 produces faster fat loss than either approach alone — typically 1.5–2 lbs per week of actual fat loss after initial water weight.
The 5:2 keto combination offers the metabolic benefits of keto with the additional weekly calorie deficit from fasting days. A powerful and flexible protocol.