The 5:2 Diet: How Much Should You Eat?
The 5:2 diet is an intermittent fasting approach where you eat normally 5 days a week and sharply cut calories on the other 2, making it easier to stick with than diets that restrict food every single day. This calculator uses the Mifflin-St Jeor formula to estimate your basal metabolic rate (BMR), applies your activity level to get total daily energy expenditure (TDEE), and then shows you the target calories for both fasting days and normal days.
How the Fasting-Day Target Is Set
Your fasting-day target is set at roughly 25% of your TDEE, a level commonly recommended for the 5:2 approach. The goal isn't complete starvation but a significant reduction that still keeps some energy intake going while giving your body a metabolic break. Normal days are calculated at your maintenance level, and you can reduce this slightly further if weight loss is your goal.
Things to Check Before You Start
Intermittent fasting may not be suitable if you have diabetes, a history of hypoglycemia or disordered eating, or are pregnant or breastfeeding. Talk to a healthcare provider before starting, and make sure to stay hydrated and get enough minerals even on fasting days.
Frequently Asked Questions
The 5:2 diet is an intermittent fasting method where you eat normally 5 days a week and sharply restrict calories on the other 2 days, typically to around 25% of your daily energy needs.
It's generally recommended to space them out, such as Monday and Thursday, with at least one normal eating day in between to reduce physical strain.
On normal days you can eat around your maintenance calorie level without overeating. This calculator's normal-day target is based on weight maintenance.