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At 6'3" and 140 lbs, your BMI is 17.5, placing you in the Underweight category. A BMI of 17.5 falls in the underweight range (below 18.5). This may indicate insufficient body mass for your height. Consulting a healthcare provider is recommended.
17.5
BMI
Underweight
Category
148-199
Healthy range (lbs)
+8 lbs
To healthy low
BMI 17.5: Underweight
| BMI | Category | Weight (lbs) | Your Status |
|---|---|---|---|
| Below 18.5 | Underweight | Below 148 lbs | You are here |
| 18.5 to 24.9 | Normal | 148 to 199 lbs | Goal range |
| 25.0 to 29.9 | Overweight | 200 to 239 lbs | - |
| 30.0+ | Obese | Above 239 lbs | - |
Your BMI of 17.5 puts you in the Underweight category for someone 6'3".
To reach the lower boundary of the healthy range (148 lbs), you would need to gain approximately 8 lbs. A safe rate of weight gain is 0.5 to 1 lb per week through a calorie surplus combined with resistance training to prioritize lean mass.
Keep in mind that BMI does not account for muscle mass. Two people at 6'3" and 140 lbs can have very different body compositions. Body fat percentage is a more precise indicator of health risk.
You would need to gain approximately 8 lbs to reach the low end of the healthy range. The healthy BMI range (18.5 to 24.9) corresponds to 148 to 199 lbs for someone 6'3". A sustainable rate of weight loss is 0.5 to 1 lb per week through a calorie deficit of 250 to 500 calories per day.
BMI is a useful screening tool but has real limitations. It does not distinguish between muscle and fat, so muscular athletes often show elevated BMI despite low body fat. It also does not account for where fat is stored. Waist-to-height ratio and body fat percentage are more precise measures. Use BMI as a starting point, not a definitive health verdict.
For someone 6'3", the healthy weight range based on BMI is 148 to 199 lbs. At 148 lbs, BMI is 18.5 (lower boundary of healthy). At 199 lbs, BMI is 24.9 (upper boundary of healthy). Below 148 lbs is underweight; above 199 lbs is overweight.
BMI only uses height and weight. Body fat percentage measures actual fat tissue as a proportion of total weight, making it more precise for body composition assessment. Two people with the same BMI of 17.5 can have very different body fat percentages depending on muscle mass. Athletes often have BMI values above 25 while maintaining low body fat. Use body fat percentage to set specific fitness goals.
To reach low end (148 lbs)
8 lbs to gain
To reach high end (199 lbs)
59 lbs to gain
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