How Many Calories Should I Eat to Lose 1 Pound a Week

The most common weight-loss question — “how many calories should I eat” — has a genuinely calculable starting answer, built on one widely-used approximation: roughly 3,500 calories equals about one pound of body fat. Understanding where that number comes from, and where it starts to break down, is more useful than just memorizing a daily target.

The basic math

A deficit of 500 calories per day, sustained for a full week, adds up to a 3,500-calorie weekly deficit — which, under the 3,500-calorie-per-pound approximation, works out to about one pound of fat loss per week. Double the daily deficit to 1,000 calories, and the same math projects roughly two pounds per week — the upper end of what’s generally considered a safe, sustainable weight-loss rate.

To find your own daily target, you first need a baseline: your maintenance calories, the amount you’d eat to keep your weight stable at your current activity level. From there, weight loss is just maintenance minus your chosen deficit — maintenance minus 500 for a roughly one-pound-a-week pace, or maintenance minus a smaller number for a slower, often more sustainable pace.

Why 3,500 calories per pound is an approximation, not a law

The 3,500-calorie figure comes from the energy density of body fat (roughly 3,500 calories per pound of pure fat tissue), and it’s a genuinely useful starting approximation — but real-world weight loss doesn’t track it with perfect linearity, for a few concrete reasons worth understanding rather than being surprised by later.

Body composition isn’t pure fat. Especially early in a weight-loss effort, some of the weight lost is water and glycogen, not fat — which is exactly why the first week or two of a new deficit often shows a larger-than-predicted drop on the scale, followed by a slower, more “textbook” pace afterward.

Maintenance calories shift as you lose weight. A smaller body burns somewhat fewer calories at rest and during activity than a larger one did, meaning the same 500-calorie deficit calculated against your starting weight gradually becomes a smaller effective deficit as you actually lose weight — one honest reason many people see their initial pace slow down over a multi-month effort even while holding their intake steady.

Adaptive metabolic changes are real, if often overstated. The body makes some genuine metabolic adjustments during a sustained deficit (sometimes called adaptive thermogenesis), modestly reducing energy expenditure beyond what the smaller body-size effect alone would predict. This effect is real but frequently exaggerated in popular discussion — it typically explains a meaningful but not dramatic slowdown, not a complete plateau, for most people at a moderate, sustainable deficit.

Setting a realistic, sustainable target

A very large deficit is not simply a faster path to the same result — beyond a certain point (commonly cited around a 1,000-calorie/day upper bound for most people, less for smaller individuals), an overly aggressive deficit becomes genuinely harder to sustain, risks more pronounced muscle loss alongside fat loss, and often triggers the kind of restrictive-then-rebound eating pattern that undermines long-term results more than a slower, steadier pace would. A moderate deficit — commonly in the 300 to 750 calorie/day range depending on starting weight and goals — is widely considered a more sustainable, realistic target for most people than an aggressive one, even though it produces a slower weekly number.

Protein intake matters specifically during a deficit, beyond just total calories: adequate protein helps preserve lean muscle mass while in a deficit, meaning more of the weight actually lost comes from fat rather than muscle — a genuinely important distinction the total-calorie number alone doesn’t capture.

Putting the numbers together

Start with your maintenance calorie estimate from the Calorie Calculator, which accounts for your BMR (resting energy burn, also available standalone via the BMR Calculator) and activity level together. Subtract your chosen deficit to find a daily target, and use the Calories Burned Calculator to add back exercise-specific burn on days you train, rather than guessing. For a protein target that supports muscle retention during the deficit, the Macro Calculator splits your calorie target into protein, carbs and fat based on your goals — the fuller picture a single calorie number alone doesn’t provide.