A calorie deficit means consistently eating fewer calories than your body burns, and it’s the only way to lose stored body fat. The fundamentals are straightforward: cut about 500 calories per day from your maintenance level, and you’ll lose roughly one pound per week. But doing it properly means setting the right size deficit, eating enough protein, managing hunger, and adjusting as your body adapts. Here’s how to get each piece right.
Calculate Your Maintenance Calories
Before you can create a deficit, you need to know how many calories your body uses in a day. This number, called your Total Daily Energy Expenditure (TDEE), combines what your body burns at rest with whatever you burn through movement and exercise.
The most reliable starting point is the Mifflin-St Jeor equation, which estimates your resting metabolic rate based on your weight, height, age, and sex:
- For women: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
- For men: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
Once you have that number, multiply it by an activity factor: 1.2 if you’re sedentary, 1.375 if you’re lightly active, 1.55 for moderate activity, 1.725 if you’re active most days, or 1.9 for very intense daily exercise. The result is your estimated TDEE. A 35-year-old woman who weighs 70 kg (154 lbs), stands 165 cm (5’5″), and exercises a few times a week would land around 2,000 calories per day.
Treat this number as a starting estimate, not gospel. Track your weight and intake for two to three weeks, then adjust based on what actually happens on the scale. If your weight holds steady, you’ve found your true maintenance number.
Set the Right Size Deficit
Cutting 500 calories per day below your TDEE is the standard recommendation for most people with weight to lose. At that pace, you’ll lose about one pound a week. The CDC notes that people who lose at a gradual, steady rate of one to two pounds per week are more likely to keep the weight off than those who lose faster.
You can split the 500 calories between eating less and moving more. Eating 300 fewer calories and burning 200 through a daily walk gets you to the same place as cutting 500 from food alone, but it gives you more flexibility with meals. What you don’t want to do is slash calories dramatically. Deficits larger than about 25% of your TDEE make it significantly harder to hold onto muscle, leave you hungrier, and tend to backfire with binge episodes or burnout within weeks.
If you have a lot of weight to lose, a larger initial deficit can be reasonable under medical guidance. But for most people, 500 calories per day (or roughly 15 to 25% below TDEE) is the sweet spot between noticeable progress and sustainability.
Prioritize Protein to Protect Muscle
When you eat fewer calories than you burn, your body pulls energy from both fat and muscle. The single most important dietary lever you have to shift that ratio toward fat loss is protein intake. Research on athletes and active individuals during calorie restriction consistently points to 1.6 to 2.4 grams of protein per kilogram of body weight per day. For someone weighing 80 kg (176 lbs), that’s 128 to 192 grams daily.
If you’re resistance training while dieting (and you should be), aiming toward the higher end of that range helps preserve lean mass. A systematic review of resistance-trained individuals found needs as high as 2.3 to 3.1 grams per kilogram of fat-free mass during energy deficits. You don’t need to calculate your fat-free mass precisely. Just aim for at least 0.7 to 1 gram per pound of body weight, spread across three to four meals, and you’ll be in the right range.
Protein also happens to be the most satiating macronutrient, so eating enough of it makes the deficit feel less punishing.
Choose Foods That Keep You Full
Hunger is the main reason people abandon a calorie deficit. The strategy that works best long-term isn’t willpower. It’s building meals around foods that take up a lot of space in your stomach without packing many calories.
Three characteristics make a food more filling per calorie: high water content, high fiber, and low energy density. Vegetables are the best example. Raw carrots are about 88% water. Grapefruit is 90% water. You can eat a huge volume of these foods for very few calories. Fruits, whole grains, legumes, and broth-based soups all score well too.
Some practical ways to apply this: increase the proportion of vegetables on your plate while decreasing the meat portion. Add vegetables to sandwiches and stir-fries. Snack on raw vegetables or whole fruit instead of packaged snacks. Start meals with a salad or a broth-based soup. These aren’t revolutionary tricks, but they reliably let you eat larger, more satisfying meals while staying within your calorie target. The difference between a 400-calorie meal that leaves you hungry and a 400-calorie meal that keeps you full for hours is almost entirely about food composition.
Account for Tracking Errors
Calorie counting is useful, but it’s never perfectly accurate. The FDA allows calorie counts on nutrition labels to vary by as much as 20% from the actual calorie content. A granola bar labeled at 200 calories could contain anywhere from 160 to 240. Restaurant meals and homemade dishes introduce even more uncertainty, since portion sizes and preparation methods vary.
This doesn’t mean tracking is pointless. It means you should build in some buffer. Weigh foods with a kitchen scale when you can, especially calorie-dense items like oils, nuts, and grains where a small measuring error can add 100+ calories. Use your body weight trend over two to three weeks as the real feedback loop. If you’re not losing at the expected rate despite consistent tracking, your actual intake is likely higher than recorded, and you need to tighten up portions or cut another 100 to 200 calories.
Understand Metabolic Adaptation
As you lose weight and spend time in a deficit, your body burns fewer calories than the original math predicted. Part of this is straightforward: a smaller body needs less energy. But part of it is an active metabolic response called adaptive thermogenesis, where your body reduces energy expenditure beyond what the lost weight alone would explain.
Research measuring this effect found that after just one week of calorie restriction, participants burned roughly 178 fewer calories per day than expected based on their body composition changes. That reduction stayed relatively stable throughout six weeks of dieting. In practical terms, a deficit that should produce one pound of fat loss per week might eventually yield only half a pound, even if you haven’t changed anything.
The solution isn’t to keep slashing calories. It’s to recalculate your TDEE periodically (every four to six weeks), incorporate strength training to maintain the metabolically active muscle tissue that keeps your resting burn higher, and consider structured breaks from the deficit.
Use Diet Breaks to Stay on Track
Eating at your full maintenance calories for a planned period can help counteract metabolic slowdown and give you a psychological reset. There are two main approaches:
- Refeeds: One to three days at maintenance calories (or 5 to 10% above), typically with extra carbohydrates. A common setup is five days of restricted eating followed by two days at maintenance.
- Diet breaks: Four or more consecutive days to several weeks at maintenance. Common ratios of dieting to break time include 4:1, 3:1, 2:1, and even 1:1 as you get leaner.
Early evidence suggests these intermittent approaches may improve fat loss efficiency and help preserve lean mass compared to continuous restriction. A practical starting point: after every three to four weeks of consistent dieting, take a full week at maintenance calories. As you get leaner and the deficit feels harder, you can increase the frequency. You’re not “quitting” during these breaks. You’re eating at the calorie level that maintains your current weight, which keeps the overall fat loss trajectory intact while giving your metabolism and your motivation a chance to recover.
Add Resistance Training
A calorie deficit without strength training tends to produce roughly equal parts fat loss and muscle loss. Adding two to four resistance training sessions per week dramatically shifts that ratio. Your body is far more likely to preserve muscle it’s actively using, so the energy deficit gets directed primarily at fat stores instead.
You don’t need an elaborate program. Compound movements like squats, deadlifts, presses, and rows, performed at a challenging intensity, provide the strongest muscle-preservation signal. Keep training volume moderate since your recovery capacity is reduced when eating less. If you’re new to lifting, you may even gain some muscle while losing fat during the first several months, especially with adequate protein.
Monitor Progress Beyond the Scale
Daily weight fluctuates by one to four pounds due to water retention, sodium intake, carbohydrate stores, and digestion. Weigh yourself at the same time each day (first thing in the morning, after using the bathroom) and track the weekly average. Comparing weekly averages gives you a reliable trend without the noise of daily swings.
Measurements around your waist, hips, and other sites can reveal fat loss that the scale misses, especially if you’re gaining muscle simultaneously. Progress photos taken every two to four weeks under consistent lighting are often more motivating than any number. If your weekly average weight is trending down by 0.5 to 1% of your body weight per week, the deficit is working properly.