Why endurance athletes need a smarter TDEE

A regular TDEE calculator gives you one number for the whole week. That number is wrong four days out of seven. On a hard ride day you can burn 1,500 kcal more than on a rest day, and your carb demand changes even more. Eating to the average means you're underfueling key sessions and overfeeding rest days, which is how athletes end up tired and slowly putting on weight at the same time.

How this planner works

The calculator runs Mifflin-St Jeor for BMR, applies your activity factor for baseline TDEE, then redistributes the week:

• Training days get +15% carbs to cover glycogen demand.
• Rest days get -20% carbs to prevent passive surplus.
• Phase multipliers shift the floor: build and peak push more carbs, taper pulls them back.
• Protein stays at 2 g/kg body weight every day. Fat fills the remainder at 25% of calories.

You enter your weight, height, age, sex, activity level, training phase, and goal. The output is a 7-day grid showing calories, protein, carbs, and fat for each training and rest day.

When to recalculate

Recalculate after a 2 kg body weight change, when you switch training phases, or when your weekly hours change by more than 25%. Mid-block, the same plan should hold for 4 to 6 weeks.