A 24-year-old woman needs roughly 1,800 to 2,400 calories per day, depending on how active she is. The U.S. Dietary Guidelines estimate 1,800 calories for sedentary women ages 21 to 25, 2,000 for moderately active women, and 2,400 for active women. These are starting points, not exact prescriptions. Your actual needs depend on your height, weight, body composition, and goals.
Calorie Estimates by Activity Level
The three activity levels used in federal guidelines map to real daily movement patterns. Sedentary means you go about your day (cooking, commuting, desk work) without intentional exercise. Moderately active is equivalent to walking 1.5 to 3 miles per day on top of your normal routine. Active means walking more than 3 miles a day or doing comparable exercise.
For women ages 21 to 25, the estimates break down simply:
- Sedentary: 1,800 calories
- Moderately active: 2,000 calories
- Active: 2,400 calories
Most people underestimate how sedentary they are. If you work at a desk and don’t exercise regularly, 1,800 calories is likely closer to your maintenance level than 2,000. On the other hand, if you strength train four or five days a week, run, or have a physically demanding job, you could need well above 2,000.
How to Calculate a More Personalized Number
The guidelines above assume an average-sized woman. If you want a number tailored to your body, the most widely used method starts with calculating your basal metabolic rate (BMR), which is the energy your body burns at complete rest just to keep you alive. The Mifflin-St Jeor equation is considered the most accurate for most women:
BMR = (9.99 × weight in kg) + (6.25 × height in cm) − (4.92 × age) − 161
For a 24-year-old woman who weighs 140 pounds (63.5 kg) and stands 5’5″ (165 cm), that works out to a BMR of about 1,370 calories. That’s what her body would burn lying in bed all day. To get her actual daily calorie needs, you multiply by a physical activity factor. The Food and Agriculture Organization defines these multipliers as 1.4 to 1.69 for a sedentary or light-activity lifestyle, 1.7 to 1.99 for a moderately active lifestyle, and 2.0 to 2.4 for a vigorously active lifestyle. Using this example, a moderately active 24-year-old at that height and weight would need around 2,330 to 2,600 calories, which is higher than the general guideline of 2,000 because the formula accounts for her specific body.
This is why generic calorie targets can miss the mark. A taller or more muscular woman burns more at rest, and the multiplier effect amplifies that difference. Running your own numbers gives you a much better baseline.
Adjusting Calories for Weight Loss or Gain
If your goal is weight loss, the standard approach is to eat about 500 fewer calories per day than your maintenance level. That creates a deficit that typically results in losing about half a pound to one pound per week. So if your calculated maintenance is 2,200 calories, eating around 1,700 would put you in a moderate deficit.
Cutting more aggressively than that often backfires. Very low calorie intakes (below about 1,200 for most women) are difficult to sustain, tend to reduce muscle mass rather than just fat, and can leave you short on essential nutrients. A gradual deficit is easier to maintain and more likely to preserve the muscle that keeps your metabolism healthy.
For weight gain, the same principle works in reverse. Adding 250 to 500 calories above maintenance, combined with resistance training, supports muscle growth without excessive fat gain.
Pregnancy and Breastfeeding Change the Math
At 24, pregnancy is a realistic consideration, and calorie needs shift significantly during this time. In the first trimester, energy requirements are generally the same as for non-pregnant women. In the second trimester, you need about 340 extra calories per day. By the third trimester, that increases to roughly 450 extra calories daily. During breastfeeding, the additional demand jumps to about 500 calories above your normal non-pregnant baseline.
These increases matter because undereating during pregnancy can affect fetal development, while overeating beyond these modest bumps contributes to excess weight gain that’s harder to lose postpartum.
Your Menstrual Cycle Affects Daily Burn
Your calorie needs aren’t perfectly static throughout the month. During the luteal phase (the roughly two weeks between ovulation and your period), your resting metabolic rate increases slightly. Your body also breaks down more protein during this phase, which contributes to higher energy expenditure. This is one reason many women feel hungrier in the days before their period. The increase is real but modest, so you don’t need to overhaul your eating. Listening to your hunger and eating a bit more during that window is a reasonable response.
Where Those Calories Should Come From
Hitting the right calorie target matters less if most of those calories come from ultra-processed food. The recommended macronutrient ranges for adults are 45 to 65 percent of calories from carbohydrates, 10 to 35 percent from protein, and 20 to 35 percent from fat. For a 2,000-calorie diet, that translates to roughly 225 to 325 grams of carbs, 50 to 175 grams of protein, and 44 to 78 grams of fat per day.
Two nutrients deserve specific attention in your mid-20s. Women in the 19 to 50 age range need 1,000 mg of calcium daily to support bone density, which peaks around age 30. Iron needs are also higher for menstruating women than for men, and falling short is one of the most common nutrient deficiencies in young women. Prioritizing iron-rich foods (red meat, lentils, spinach, fortified cereals) and calcium sources (dairy, fortified plant milks, leafy greens) gives you the best return on those calories.
Protein tends to be the macronutrient most young women undereat, especially if they’re active. Aiming for the higher end of the protein range (closer to 25 to 30 percent of calories) supports muscle maintenance, keeps you fuller between meals, and helps preserve lean mass if you’re in a calorie deficit.