How Many Calories Should I Eat to Lose Weight? A Science-Based Guide

To lose one pound of fat per week, you need to eat approximately 500 fewer calories per day than your body burns—creating a weekly deficit of 3,500 calories. For most adults, this means consuming between 1,200 and 1,800 calories daily for women, or 1,500 and 2,200 for men, depending on age, height, weight, and activity level.

But here's the thing: that's a starting point, not a final answer. The "right" number of calories for you depends on factors that generic calculators can't fully capture. Let's break down exactly how to find your personal calorie target—and more importantly, how to make it work in real life.

Understanding TDEE: Your Body's Daily Energy Budget

Before you can figure out how much to eat for weight loss, you need to understand how much your body burns. This is called your Total Daily Energy Expenditure (TDEE)—the total number of calories you burn in a day through all activities combined.

Your TDEE is made up of four components:

• Basal Metabolic Rate (BMR): The calories your body burns at complete rest just to stay alive—breathing, circulating blood, maintaining body temperature. This accounts for 60-75% of total daily burn for most people.
• Thermic Effect of Food (TEF): The energy used to digest, absorb, and process the food you eat. This accounts for roughly 10% of your TDEE.
• Exercise Activity Thermogenesis (EAT): Calories burned during intentional exercise—gym workouts, runs, sports, etc.
• Non-Exercise Activity Thermogenesis (NEAT): Everything else—walking to your car, fidgeting, standing, taking the stairs. This can vary by 500-2,000 calories between individuals.

How to Estimate Your TDEE

The most accurate method is to track your food intake and weight for 2-3 weeks. If your weight stays stable, your average calorie intake equals your TDEE. But if you need a starting point right now, you can use the Mifflin-St Jeor equation, which research has shown to be the most accurate formula for estimating BMR.

Example: A 35-year-old woman who is 5'6" (167 cm), weighs 160 lbs (73 kg), and exercises 3 times per week would have a BMR of approximately 1,430 calories. Multiplied by 1.55 (moderately active), her estimated TDEE would be around 2,215 calories per day.

Creating Your Calorie Deficit

Once you know your TDEE, weight loss becomes straightforward math. To lose fat, you need to eat fewer calories than you burn. The size of your deficit determines how fast you lose weight:

For our example woman with a TDEE of 2,215 calories, a moderate 500-calorie deficit would put her target at 1,715 calories per day to lose about one pound per week.

The Minimum Calorie Floor

Going too low is counterproductive. Most health organizations recommend women eat no fewer than 1,200 calories and men no fewer than 1,500 calories per day without medical supervision. Below these levels:

• You risk nutrient deficiencies
• Your metabolism may slow significantly (adaptive thermogenesis)
• Muscle loss accelerates
• Energy and mood plummet
• Sustainability becomes nearly impossible

If a 500-calorie deficit would put you below these minimums, either accept a smaller deficit or increase your TDEE through more activity.

Why Calculators Are Just a Starting Point

Here's what online calculators can't account for: individual variation is enormous. Two people with identical stats can have TDEEs that differ by 500+ calories due to differences in NEAT, hormonal profiles, gut microbiome, and metabolic efficiency.

This is why the most successful approach is to:

• Start with a calculated estimate
• Track your intake consistently for 2-3 weeks
• Monitor your weight (weekly averages, not daily fluctuations)
• Adjust based on real results

If you're eating 1,700 calories and losing 1 lb per week, you've found your sweet spot. If you're not losing, you either need to reduce intake by 100-200 calories or your tracking isn't accurate (the more common issue).

The Tracking Accuracy Problem

Research consistently shows that people underestimate their calorie intake by 30-50%. Even dietitians underreport by about 10%. The calories you think you're eating and the calories you're actually eating can be wildly different.

Common tracking mistakes:

• Forgetting cooking oils (120 calories per tablespoon)
• Eyeballing portions instead of measuring
• Not counting "just a bite" or "just a taste"
• Using incorrect database entries
• Forgetting beverages, sauces, and condiments

This is why consistent, accurate tracking matters more than finding the "perfect" calorie number. A rough target with precise tracking beats a precise target with rough tracking every time.

Adjusting as You Lose Weight

Your calorie needs aren't static. As you lose weight, your TDEE decreases because there's less of you to fuel. A person who goes from 200 lbs to 170 lbs might see their TDEE drop by 200-300 calories.

This is why weight loss often stalls after initial success—you've hit a new equilibrium. When this happens, you have two options:

• Reduce calories further (if you're not already at the minimum)
• Increase activity (especially NEAT—more walking, standing, movement)

Recalculating your TDEE every 10-15 pounds lost will help you stay on track.

Protein: The Non-Negotiable

When you're in a calorie deficit, your body doesn't just burn fat—it can also break down muscle for energy. The best defense is adequate protein intake: aim for 0.7-1 gram per pound of body weight (or per pound of goal weight if you have significant fat to lose).

Protein also has the highest thermic effect of any macronutrient (your body burns 20-30% of protein calories just digesting it) and is the most satiating, helping you feel fuller on fewer calories.

How Kalo Simplifies the Process

The math of weight loss is simple. The execution is where most people struggle. Tracking every meal manually is tedious, and that's exactly why most people quit within two weeks.

Kalo removes the friction. Snap a photo of your meal, and AI-powered recognition instantly estimates your calories and macros—no searching databases, no weighing every ingredient, no guessing portion sizes. The faster and easier tracking becomes, the more consistently you'll do it.

And consistency, not perfection, is what drives results. A tracked 1,700-calorie day beats an untracked "I think I did okay" every single time.

Frequently Asked Questions

How many calories should I eat to lose 2 pounds a week?

You need a daily deficit of about 1,000 calories. For most people this is aggressive — if it drops you below 1,200 (women) or 1,500 (men), aim for a smaller deficit and increase activity instead.

Is 1,200 calories a day enough?

1,200 is generally the minimum for women without medical supervision. Most women do better on 1,400-1,800 depending on activity level and body size, as too-low intake increases muscle loss and metabolic adaptation.

Why am I not losing weight on 1,500 calories?

The most common reason is inaccurate tracking — what you think is 1,500 may be closer to 2,000. Other causes: metabolic adaptation, water retention masking fat loss, or a TDEE lower than expected.

Should I eat back exercise calories?

Eat back only about 50%. Fitness trackers overestimate calories burned by 30-50%. Eating back all reported exercise calories can eliminate your deficit entirely.

Sources

• Mifflin-St Jeor equation for BMR — American Journal of Clinical Nutrition (1990)
• Accuracy of self-reported dietary intake — JADA (2002)
• Dietary protein on body composition during energy restriction — Journal of Nutrition (2005)
• Adaptive thermogenesis and metabolic adaptation — Obesity (2013)