Why you're not losing weight in a calorie deficit

1. You're eating more than you log

This is the big one, and it isn't a willpower problem. In a well-known study in the New England Journal of Medicine, people who said they couldn't lose weight on low calories under-reported what they ate by 47% and over-reported their exercise by 51%.

The calories hide in cooking oil, sauces, drinks, bites while cooking, and weekends.

• Weigh food for one week instead of guessing portions.
• Log oil and butter every time. A tablespoon of oil is about 120 calories.
• Count weekends. Two big days can erase five careful ones.

2. Your activity level is set too high

Most people pick an activity level one step higher than they really are. A desk job with three gym sessions a week is usually Light, not Moderate. That one click can add 200–300 calories to your target.

• Use your daily steps: under 5,000 is Sedentary, 5,000–7,500 is Light.
• Recalculate one level lower and use that number for two weeks.

3. You're eating back your exercise calories

Your TDEE already includes your workouts, through your activity level. If your watch or app then "adds back" exercise calories, you count them twice. Fitness trackers also tend to overestimate what a workout burns, so the extra food is often more than the workout used.

• Eat to your target and ignore the "calories earned" number.

4. Water is hiding your fat loss

Your weight can swing 2–4 lb in a day from salt, carbs, hormones, stress and new workouts. Your body stores carbs with about 3 grams of water per gram, so a pasta night can show up on the scale the next morning even though you didn't gain fat.

• Weigh in 3–4 mornings a week, after the bathroom, before eating.
• Compare weekly averages, not single days.
• Give a new plan at least 3–4 weeks before judging it.

5. Your TDEE went down as you lost weight

A smaller body burns fewer calories. After losing 10–20 lb, the deficit that worked at the start can shrink to almost nothing. Your body also nudges you to move a little less, without you noticing.

• Recalculate every 10–20 lb (5–10 kg), or every 4–6 weeks.
• Keep your steps up; they're the easiest part of your burn to protect.

6. Your meals change too much day to day

Variety makes calories harder to track. A 2026 study published by the American Psychological Association found people who repeated go-to meals lost 5.9% of their body weight in 12 weeks, versus 4.3% for people who ate a wider variety. Steadier daily calories also went with better results.

• Pick a go-to breakfast and lunch and repeat them on weekdays.

When to talk to a doctor

If you've weighed and logged carefully for 4 weeks, eaten at a sensible deficit, and your weekly average hasn't moved, check in with your doctor. Thyroid problems, PCOS, some medications (such as steroids and certain antidepressants) and fluid retention can all play a part. Don't keep cutting calories: going below about 1,200 a day (women) or 1,500 (men) needs medical supervision.

Your plan for this week

1. Recalculate your TDEE, one activity level lower if unsure.
2. Weigh and log everything for 7 days, including oil and drinks.
3. Stop eating back exercise calories.
4. Weigh in 3–4 mornings and compare weekly averages.

Sources

1. Lichtman SW et al. Discrepancy between self-reported and actual caloric intake and exercise in obese subjects. NEJM, 1992.
2. American Psychological Association. Want to lose weight? Try eating the same meals on repeat. March 2026.
3. Gundersen Health System. Should I eat back my exercise calories?