Training vs Rest Day: Why Your Body Needs Different Fuel

When it comes to fitness and nutrition, one of the most overlooked truths is this: your body doesn’t burn the same amount of energy every day. Training days and rest days have completely different demands, and fueling your body.

Westerterp (2017), in European Journal of Clinical Nutrition, analysed data showing that activity-induced energy expenditure (AEE) can vary by more than 500–800 kcal/day between training and rest days in active adults. He noted that while basal metabolic rate (BMR) remains relatively stable, AEE accounts for up to 30–50% of total daily energy expenditure — the most variable component. The study also highlighted compensatory mechanisms such as reduced spontaneous movement or improved efficiency after heavy training, which can offset part of the calorie burn. This demonstrates that static daily calorie targets fail to reflect real-world fluctuations.

That’s where the Foody U Calculator comes in. Instead of giving you one static number for your daily calories, it adapts your plan based on your training, your work, your lifestyle, and your goals — just like a real sports nutritionist would.

Why Training and Rest Days Shouldn’t Look the Same

On a training day, your muscles demand more energy and nutrients to fuel performance and speed up recovery. Carbs are especially important for powering workouts, while protein supports repair and growth.

On a rest day, your calorie needs are lower, but that doesn’t mean nutrition is less important. The focus shifts towards recovery, maintaining lean muscle, and supporting your body’s natural processes.

Most apps miss this distinction. They give you one “calories per day” target and expect it to work for every situation. Foody U fixes this.

How the Foody U Calculator Works

The Calculator is the first step when you join Foody U. It walks you through a series of quick questions to build a precise picture of your lifestyle and training.

Step 1. Your sport

Select your main sport so Foody U can calculate the energy demands specific to your training.

Step 2. Activity at work

Choose your workday activity level — from sitting at a desk to heavy labour.

Step 3. Activity at leisure

Account for daily movement like walking, light exercise, or being mostly sedentary.

Step 4. Body fat %

Estimate your body fat using simple visuals to calculate your metabolism more accurately.

Step 5. Your goal

Decide what you want to achieve: muscle gain, fat loss, performance, or staying toned.

Step 6. Diet type

Select a diet that matches your preferences — omnivore, pescatarian, vegetarian, or vegan.

The Science Behind It

Foody U doesn’t just guess your numbers. It calculates:

• Basal Metabolic Rate (BMR): The calories your body needs at rest.

• Physical Activity Level (PAL): The energy used for daily non-sport activities.

• Sport Energy Expenditure (MET): Calories burned from your chosen sport, based on intensity, duration, and body weight.

Unlike most apps, Foody U separates training from everyday movement, so you get two precise plans: one for training days, one for rest days.

See the science behind your plan — BMR, activity expenditure, and sport energy explained clearly.

The Payoff: Your Personal Plan

Once you finish, you don’t just get a number — you get a plan built for your lifestyle:

• Daily targets → Calories, protein, carbs, and fats.

• Training vs rest day split → Two tailored plans.

• Meal breakdown → How much energy to eat at breakfast, snacks, lunch, and dinner.

• Micronutrient insights → Vitamins and minerals mapped against recommended intakes.

Your complete daily breakdown, with recipes and nutrient insights ready to use instantly.

This means you wake up knowing exactly what to eat — whether you’re heading to the gym or taking a rest day.

Why This Matters for You

• Avoid overeating on rest days.

• Avoid under-fueling on training days.

• Perform better and recover faster.

Try It Yourself

The Foody U Calculator is free to try inside the app. In just a few minutes, you’ll know your training day and rest day needs — and you’ll have a personalised meal plan built for your goals.

👉 Try Foody U for free