To lose weight safely, most people need to eat a bit below their normal maintenance calories for their age, sex, and activity level—usually a deficit of about 300–500 calories per day, not a single fixed number for everyone.

Key idea: calorie deficit, not one magic number

  • Weight loss happens when you consistently eat fewer calories than your body burns.
  • A common safe target is a 300–500 calorie daily deficit, which often leads to about 0.25–0.5 kg (0.5–1 lb) loss per week for many adults.
  • The “right” number depends on:
    • Age
    • Sex
    • Height and current weight
    • Activity level
    • Health conditions (thyroid, medications, pregnancy, etc.)

For most people, “how many calories should I eat a day by age to lose weight” really means: start from age‑based maintenance calories, then subtract a moderate deficit.

Typical daily maintenance calories by age (then subtract 300–500)

Below are rough maintenance ranges (to keep weight the same) from large guidelines; to lose weight, many people aim about 300–500 calories below the midpoint of their range, after checking with a doctor or dietitian.

html

<table>
  <caption>Approximate daily maintenance calories by age (moderately active)</caption>
  <thead>
    <tr>
      <th>Age group</th>
      <th>Women – maintain</th>
      <th>Men – maintain</th>
      <th>Example daily target to lose weight*</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>16–18</td>
      <td>1,800–2,400 kcal/day [web:5]</td>
      <td>2,400–3,200 kcal/day [web:5]</td>
      <td>Midpoint minus ~400 kcal (for example: W ~1,900; M ~2,300)**</td>
    </tr>
    <tr>
      <td>19–25</td>
      <td>2,000–2,400 kcal/day [web:1][web:5]</td>
      <td>2,600–3,000 kcal/day [web:1][web:5]</td>
      <td>W ~1,600–1,900; M ~2,100–2,400 kcal/day</td>
    </tr>
    <tr>
      <td>26–30</td>
      <td>1,800–2,400 kcal/day [web:5][web:7]</td>
      <td>2,400–3,000 kcal/day [web:1][web:5][web:7]</td>
      <td>W ~1,500–1,900; M ~2,000–2,400 kcal/day</td>
    </tr>
    <tr>
      <td>31–50</td>
      <td>1,800–2,200 kcal/day [web:1][web:5][web:7]</td>
      <td>2,200–3,000 kcal/day [web:1][web:5][web:7]</td>
      <td>W ~1,400–1,800; M ~1,800–2,400 kcal/day</td>
    </tr>
    <tr>
      <td>51–59</td>
      <td>1,600–2,200 kcal/day [web:1][web:5]</td>
      <td>2,200–2,800 kcal/day [web:5][web:7]</td>
      <td>W ~1,300–1,700; M ~1,800–2,200 kcal/day</td>
    </tr>
    <tr>
      <td>60–75</td>
      <td>1,600–2,000 kcal/day [web:1][web:5][web:7]</td>
      <td>2,000–2,600 kcal/day [web:1][web:5][web:7]</td>
      <td>W ~1,300–1,600; M ~1,600–2,100 kcal/day</td>
    </tr>
    <tr>
      <td>76+</td>
      <td>1,600–2,000 kcal/day (similar to 61+ ranges) [web:1][web:5]</td>
      <td>2,000–2,400 kcal/day [web:5]</td>
      <td>Deficits must be small; get medical guidance</td>
    </tr>
  </tbody>
</table>

*These example “lose weight” targets are general illustrations only; individual needs can be higher or lower.

**Example: if a 20‑year‑old man maintains on ~2,800 kcal/day, a typical weight‑loss target might be ~2,300–2,500 kcal/day.

How to personalize your number

Because age is only one factor, the best practice is to personalize your calorie target:

  1. Use a calculator
    • Reputable calorie calculators ask for age, sex, height, weight, and activity to estimate maintenance calories.
 * Then you choose a deficit (for example 10–20% fewer calories than maintenance).
  1. Adjust slowly
    • Track weight and how you feel for 2–3 weeks:
      • If weight is not changing, your “maintenance” estimate was probably too high and you may need a slightly larger deficit.
      • If weight is dropping very fast, energy is low, or hunger is extreme, your deficit may be too aggressive.
  1. Stay within safe limits
    • Many guidelines caution most women not to drop below about 1,200 kcal/day and most men not below about 1,500 kcal/day without medical supervision, because of nutrient deficiency and health risk.

What people on forums usually say

In weight‑loss forums and communities, people tend to converge on a few themes:

  • “There’s no perfect number”
    • Members often stress that calculators are starting points and that you must watch real‑world results and adjust.
  • “Track accurately”
    • People frequently recommend:
      • Using a food scale
      • Logging meals consistently
      • Being honest about snacks and drinks, which often hide more calories than expected.
  • “Slow and steady wins”
    • Many long‑term success stories describe modest daily deficits, regular walking or lifting, and focusing on sustainable habits rather than crash diets.

Practical steps to start today

  • Step 1: Write down your details (age, sex, height, weight, activity) and use a trusted online calculator to estimate maintenance calories.
  • Step 2: Subtract ~300–500 calories from that number, being careful not to go below safe minimums.
  • Step 3: Track your intake for at least 2 weeks and weigh yourself 1–2 times per week under similar conditions.
  • Step 4: If you have any medical issues, are on medications, are pregnant or breastfeeding, or are older, talk to a healthcare professional before starting a calorie deficit.

If you share your age, sex, height, weight, and activity level, a more tailored calorie range for weight loss can be outlined (still within safe, general‑information limits).