Most people will lose weight eating between 1,500 and 2,000 calories a day, but the right number for you depends on your size, age, sex, and how much you move. There’s no single calorie target that works for everyone. The goal is to eat less than your body burns each day while staying above a safe minimum: 1,200 calories for women and 1,500 for men.
How Your Body Burns Calories
Your body uses energy around the clock, even while you sleep. The calories it needs just to keep your organs running, your blood pumping, and your cells functioning make up your resting metabolic rate. For most adults, this accounts for 60 to 75 percent of total daily calorie burn. On top of that, you burn calories through physical activity, digesting food, and all the small movements you make throughout the day, like walking to the kitchen, fidgeting, or standing at your desk.
That last category, called non-exercise activity, varies enormously from person to person. Two people of the same size, age, and sex can differ by up to 2,000 calories a day in how much energy they burn through everyday movement alone. Someone with a desk job might burn around 700 calories a day from non-exercise movement, while someone in a physically demanding job could burn 2,000 or more. This is one reason your coworker can eat more than you and still not gain weight.
How to Estimate Your Number
The most reliable starting point is to calculate your resting metabolic rate using the Mifflin-St Jeor equation, which research has found to be the most accurate formula available. It uses four variables: your weight in kilograms, height in centimeters, age, and sex.
- For women: (9.99 × weight) + (6.25 × height) − (4.92 × age) − 161
- For men: (9.99 × weight) + (6.25 × height) − (4.92 × age) + 5
That gives you the calories your body burns at rest. To account for your activity level, multiply the result by one of these factors:
- Sedentary (desk job, little exercise): 1.2
- Lightly active (light exercise 1–3 days/week): 1.375
- Moderately active (moderate exercise 3–5 days/week): 1.55
- Very active (hard exercise 6–7 days/week): 1.725
The result is roughly how many calories you burn in a total day. To lose weight, you eat less than that number. A deficit of 500 calories per day is a common starting point, though as you’ll see below, weight loss doesn’t follow a perfectly linear path.
Here’s a practical example. A 40-year-old woman who weighs 170 pounds (77 kg), stands 5’5″ (165 cm), and has a desk job would calculate a resting rate of about 1,387 calories. Multiplied by 1.2 for a sedentary lifestyle, her total daily burn is roughly 1,665 calories. A 500-calorie deficit would put her at around 1,165, which falls below the 1,200 minimum. In this case, she’d aim for 1,200 calories and accept a slightly slower rate of loss, or increase her activity to widen the gap.
Why the “3,500 Calories Per Pound” Rule Is Wrong
You’ve probably heard that cutting 3,500 calories equals one pound of fat lost. This rule has appeared in textbooks and government websites for decades, but it significantly overestimates how much weight you’ll actually lose. When researchers compared the rule’s predictions against real weight loss in tightly controlled experiments, people lost an average of 7.4 pounds less than the rule predicted.
The problem is that your body isn’t a static machine. As you eat less and weigh less, your metabolism adjusts. Your body starts conserving energy in ways that go beyond just the smaller body burning fewer calories. After just one week of calorie restriction, people’s metabolic rates dropped by an average of 178 calories per day more than their change in body size would explain. Some individuals saw drops as large as 379 calories per day, while a lucky few experienced almost no slowdown at all.
This metabolic adaptation happens through shifts in hormones related to thyroid function, insulin, and appetite signaling. It’s the reason weight loss tends to slow down after the first few weeks even when you’re sticking to the same calorie target. It’s normal, not a sign you’re doing something wrong.
A Realistic Rate of Loss
The CDC recommends aiming for 1 to 2 pounds per week. People who lose weight at this gradual pace are more likely to keep it off than those who drop weight quickly. Even a 5 percent reduction in body weight, which is 10 pounds for a 200-pound person, can produce meaningful health improvements.
Because of metabolic adaptation, weight loss follows a curve rather than a straight line. You’ll likely lose more in the first two weeks (partly water weight) and then settle into a slower, steadier pace. If your weight stalls after several weeks, your body’s new, lower calorie needs may have caught up to what you’re eating. At that point, a small further reduction in calories or an increase in activity can restart progress.
What to Eat on Fewer Calories
When you’re eating less food overall, the quality of those calories matters more than ever. Two nutrients in particular help you stay full and preserve muscle on a deficit: protein and fiber.
Protein needs increase when you’re losing weight because your body is more likely to break down muscle tissue in a calorie deficit. People who exercise regularly do well with 1.1 to 1.5 grams of protein per kilogram of body weight daily, while those who lift weights benefit from 1.2 to 1.7 grams per kilogram. For a 170-pound person, that translates to roughly 85 to 130 grams per day. Spreading protein across meals, aiming for 15 to 30 grams per meal, appears more effective than loading it all into dinner. Some research suggests that shifting more protein to breakfast specifically helps reduce hunger and cravings throughout the day.
Fiber is the other piece worth paying attention to. In a 16-week study, increased fiber intake was a consistent and strong predictor of weight loss, with people who ate more vegetables and fruits losing more weight overall. Aiming for around 40 grams of fiber per day from vegetables, fruits, legumes, and whole grains helps you feel satisfied on fewer calories because fiber-rich foods are bulky and take longer to digest.
Safe Minimums and Red Flags
Calorie intake should not drop below 1,200 a day for women or 1,500 a day for men without medical supervision. Below those thresholds, it becomes very difficult to get enough vitamins, minerals, and essential nutrients from food alone. Diets providing fewer than 800 calories per day are classified as very low-calorie diets and are only appropriate for people with a BMI of 30 or higher (or 27 with serious health conditions like diabetes or sleep apnea) who haven’t succeeded with less aggressive approaches. These diets require close medical monitoring.
Signs you’ve cut too aggressively include persistent fatigue, hair loss, feeling cold all the time, irritability, loss of menstrual periods, and difficulty concentrating. If you experience these, you’re likely eating too little rather than too much. A more moderate deficit sustained over a longer period will produce better results than a steep cut you can’t maintain.
Putting It All Together
Start by calculating your total daily calorie burn using the formula and activity multiplier above. Subtract 500 calories to create a moderate deficit, but don’t go below the safe minimums of 1,200 or 1,500. Prioritize protein at every meal and build your plates around high-fiber vegetables and fruits. Expect faster loss in the first couple of weeks, then a natural slowdown as your metabolism adapts. If progress stalls, make small adjustments rather than drastic cuts. The calorie target that works best is the one you can sustain for months, not the lowest number you can white-knuckle through for a week.