MariposasCalorie Deficit Explained: How to Lose Fat Sustainably
By Zachary, builder of Mariposas · Reviewed against published exercise-science sources (references)
· Last updated June 2026
Every diet that works, works for one reason: it puts you in a calorie deficit. Understand that and you can stop chasing gimmicks.
What a calorie deficit is
A calorie deficit means eating fewer calories than your body burns, so it taps stored fat for the difference. It’s the non-negotiable requirement for fat loss, regardless of which diet style you use to get there.
How big should it be?
A moderate deficit of roughly 300-500 calories a day yields steady fat loss of about half a pound to a pound a week while preserving muscle and sanity. Bigger deficits lose more in the short term but are harder to sustain and cost more muscle.
Make it sustainable
- Keep protein high to protect muscle and stay full
- Build meals from filling, high-volume foods
- Strength train so you lose fat, not muscle
- Expect plateaus, they’re normal, not failure
Find your numbers
Start by estimating your maintenance calories with our TDEE calculator, then subtract a moderate deficit.
Sources: Mifflin MD, St Jeor ST et al
⚕️ General fitness information only, not professional, medical, or nutritional advice. We are not doctors or dietitians. Talk to a qualified professional before starting a new exercise or nutrition program, especially if you have an injury or health condition.
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