Calorie Calculator
Discover your personalised daily calorie target using the Mifflin-St Jeor formula — then see exactly how GutSlim Diet Shake fits into your weight loss plan.
Takes 30 seconds · No account needed
4
Calorie targets calculated
516 kJ
Diet Shake per serving
22.7g
Protein in Diet Shake
0.5kg
Safe weekly loss target
Why Knowing Your Calories Changes Everything
Most people trying to lose weight are either eating too much, eating too little, or have no idea which one — a personalised calorie target ends the guessing.
Set a precise deficit
The science is clear: sustainable fat loss requires a consistent calorie deficit. Knowing your exact TDEE makes this precise — not guesswork.
Choose your pace
Mild, moderate, or aggressive loss? Our calculator shows four deficit levels so you choose the pace that fits your lifestyle and goals.
Understand your metabolism
Your TDEE (Total Daily Energy Expenditure) is unique to your age, weight, height, and activity level. Generic '1200 calories' advice ignores all of this.
Meal replacement guidance
See exactly how GutSlim Diet Shake fits into your daily calorie target — replacing a meal with 22.7g protein at just 516 kJ.
How Our Calculator Works
Mifflin-St Jeor Formula
Our calculator uses the Mifflin-St Jeor equation — widely considered the most accurate BMR formula for most people by registered dietitians worldwide.
Activity-adjusted TDEE
BMR alone doesn't account for how active you are. We multiply by your activity level to get your true Total Daily Energy Expenditure.
Four deficit options
We calculate four intake targets: maintenance, mild loss (0.25kg/wk), recommended loss (0.5kg/wk), and aggressive loss (0.75kg/wk) — you decide.
How GutSlim Diet Shake Fits Your Calorie Target
Once you know your daily calorie target, meal planning becomes simple. GutSlim Diet Shake is specifically designed to replace one meal per day at just 516 kJ — making your calorie deficit achievable without feeling hungry or deprived.
Why Your Gut Affects How Your Calories Work
Calorie counting alone doesn't explain why two people eating the same amount can have completely different weight outcomes. Your gut microbiome is a critical — and often ignored — variable.
What Your Results Show
Maintenance
Maintain current weight
2,100 cal
Mild Loss (0.25kg/wk)
Sustainable & gentle
1,850 cal
Weight Loss (0.5kg/wk)
Recommended with GutSlim
1,600 cal
Aggressive Loss (0.75kg/wk)
Consult healthcare provider
1,350 cal
Example results — your actual numbers depend on your individual profile.
Frequently Asked Questions
What is TDEE and why does it matter?
TDEE stands for Total Daily Energy Expenditure — the total number of calories your body burns in a day including all physical activity. It's the foundation of any weight management plan: eat below your TDEE to lose weight, at your TDEE to maintain.
How accurate is the calculator?
The Mifflin-St Jeor formula is the most validated BMR equation and is widely used by registered dietitians. Activity multipliers introduce some variability, but the results are generally within 10–15% of your true TDEE — accurate enough for practical planning.
What deficit should I choose?
For sustainable, muscle-preserving fat loss, the 'Weight Loss' option (500 cal/day deficit = 0.5kg/wk) is the evidence-based sweet spot. More aggressive deficits increase muscle loss risk; gentler deficits are great for long-term maintenance.
How does GutSlim Diet Shake help hit my target?
At only 516 kJ (roughly 123 calories) per serving with 22.7g protein, the Diet Shake replaces a 400–600 calorie meal while providing superior protein, prebiotics, and live probiotics — making your calorie target easy to hit without feeling deprived.