A daily caloric deficit of 500 calories is the most widely recommended starting point for weight loss, producing roughly half a pound to one pound of loss per week. Doubling that to a 1,000-calorie daily deficit can push the rate closer to two pounds per week, which is generally considered the upper limit of what’s safe and sustainable. The right number for you depends on how much you currently eat, how active you are, and how much weight you have to lose.
The 500-Calorie Starting Point
The 500-calorie deficit became the standard recommendation because of a long-standing rule: 3,500 calories roughly equals one pound of body fat, so cutting 500 calories a day for seven days should produce about a pound of loss. In practice, the math isn’t quite that clean. Your body isn’t a simple calculator. Factors like your gut microbiome, your genetics, hormonal signals from your brain, and how long you’ve been dieting all influence how your body responds to eating less. Still, a 500-calorie daily deficit remains a useful and well-supported benchmark.
Harvard Health recommends a deficit of 500 to 1,000 calories per day for a loss rate of one to two pounds per week, and the CDC confirms that one to two pounds weekly is the pace most associated with keeping the weight off long-term. Going beyond a 1,000-calorie deficit without medical supervision increases the risk of nutrient deficiencies, fatigue, and muscle loss.
How to Find Your Number
Before you can create a deficit, you need to know how many calories your body burns in a day. This is your total daily energy expenditure, and it combines two things: the calories your body uses just to stay alive (breathing, pumping blood, maintaining body temperature) and the calories you burn through movement and exercise.
The most accurate formula for estimating your resting calorie burn is the Mifflin-St Jeor equation, which has been shown to predict within 10% of measured values more reliably than other formulas. It works like this:
- 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, you multiply it by an activity factor: 1.2 if you’re mostly sedentary, 1.375 if you’re lightly active, 1.55 for moderate activity, and 1.725 or higher if you exercise hard most days. The result is your estimated daily calorie burn. Subtract 500 from that number and you have your daily calorie target for losing about a pound a week.
For example, a 40-year-old woman who weighs 170 pounds (77 kg), stands 5’5″ (165 cm), and exercises a few times a week might have a resting burn around 1,370 calories. Multiplied by 1.55 for moderate activity, her total daily burn lands near 2,125. Eating around 1,625 calories a day would put her in a 500-calorie deficit.
Minimum Calorie Floors
No matter how eager you are to see results, there’s a floor you shouldn’t go below without medical guidance. Women should generally not eat fewer than 1,200 calories per day, and men should stay at or above 1,500. Dropping lower than these thresholds makes it extremely difficult to get adequate vitamins, minerals, fiber, and protein from food alone, and it increases the chance your body will start breaking down muscle for energy rather than relying on fat stores.
If a 500-calorie deficit would put you below these floors, a smaller deficit combined with more physical activity is a safer approach. Adding 30 minutes of exercise on most days can contribute to your deficit without requiring you to eat dangerously little.
Why Your Deficit Stops Working Over Time
One of the most frustrating parts of a caloric deficit is the plateau. You do everything right for weeks or months, and then the scale stops moving. Part of this is simple physics: a smaller body burns fewer calories, so the deficit that worked at 220 pounds won’t produce the same results at 198 pounds.
But there’s another layer. Researchers have documented something called metabolic adaptation, where your body’s calorie burn drops more than you’d expect based on weight loss alone. A person who goes from 220 to 198 pounds might expect their daily burn to fall from 2,500 to about 2,200 calories. When measured in a metabolic chamber, though, their actual burn might be closer to 2,000. That 200-calorie gap between the expected and actual burn is metabolic adaptation at work. A 2022 study in the journal Obesity found that people with greater metabolic adaptation during weight loss needed more time to reach their goals and lost less fat overall.
The encouraging news is that metabolic adaptation doesn’t appear to doom you to regaining weight. Despite a widespread belief that “the body fights back” after weight loss, no study has actually demonstrated a link between metabolic adaptation and weight regain. The plateau is real, but it’s not a trap. It simply means your deficit needs to be recalculated as your body changes.
Protecting Muscle While Losing Fat
When you eat fewer calories than you burn, your body pulls energy from both fat and muscle tissue. Losing muscle slows your metabolism further and leaves you weaker, which is exactly the opposite of what most people want. The single most effective way to protect muscle during a deficit is eating enough protein.
Current guidelines for muscle preservation during weight loss recommend 0.7 to 1.0 grams of protein per pound of body weight per day. For a 170-pound person, that means 119 to 170 grams of protein daily. This is significantly more than what most people eat without thinking about it. Spreading protein intake across meals (rather than loading it all into dinner) and combining it with some form of resistance training gives your muscles the strongest signal to stick around while your body sheds fat.
Moderate Deficits Are Easier to Maintain
The best deficit is the one you can actually sustain. A randomized controlled trial comparing intermittent calorie restriction (like the 5:2 diet, where you eat very little two days a week) against continuous moderate restriction found no significant difference in weight loss at the two-year mark. Both groups lost roughly 4 to 5% of their starting weight. But the people who had been assigned to a steady, moderate daily deficit were far more likely to still be following their plan after the structured study ended. Only about a third of those in the continuous group had stopped their diet, compared to over 70% in the intermittent group.
Among those who stuck with their approach, the results were dramatically better: participants who continued their diet maintained a 5.7% weight loss, while those who abandoned it kept off only about 1%. The pattern is consistent across weight loss research. The size of your deficit matters less than your ability to maintain it month after month. A 300-calorie deficit you follow for a year will outperform a 1,000-calorie deficit you abandon after six weeks.
Adjusting Your Deficit as You Progress
Your caloric deficit isn’t something you set once and forget. As you lose weight, your body burns fewer calories at rest. Every 10 to 15 pounds of loss typically means you need to shave another 50 to 100 calories from your target, or add more movement, to maintain the same rate of loss. Recalculating every month or so keeps your expectations realistic and prevents the frustration of a stall you don’t understand.
The rate of loss also naturally slows as you get closer to a healthy weight. Early losses of 1.5 to 2 pounds per week often taper to half a pound per week as you approach your goal. This doesn’t mean your approach has failed. It means your body has less excess energy to give up, and the process is working exactly as expected.