There isn’t one “ideal” number; healthy weight for a 15-year-old girl sits in a range based on height, age, and BMI-for-age percentiles.

To reduce belly fat, aim for 150–300 weekly minutes of running (or 75–150 vigorous) plus two strength days and a modest calorie deficit.

For a 16-year-old girl, healthy weight depends on height and growth stage; use BMI-for-age percentiles and build steady habits, not chase one number.

At age 20, a healthy weight depends on height and body makeup; use BMI 18.5–24.9 and waist measures to gauge health risk, not one “ideal” number.

Most health bodies advise no more than 1 drink a day for women or 2 for men; some, like WHO, say no level is truly safe.

For salicylic acid use, start at 0.5–1% once daily (or every other day) on the face, then step up to 2% only if skin stays calm.

Use a pea-size amount of tretinoin for the full face, starting a few nights a week and building to nightly as your skin adjusts.

For healthy indoor humidity, aim for 30–50% RH year-round and stay below 60% to curb mold and mites.

For 17-year-olds, a healthy weight depends on height and sex; doctors use BMI-for-age percentiles to judge ranges, not a single number.

For a 14-year-old girl, healthy weight depends on height and BMI-for-age percentile; use growth charts to estimate a personal range.