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Obesity and Weight Management

Need to lose weight

04/26/2006

Question:

I am 39 years and weigh 250lbs and 5.5. Most of my weight is in the middle, stomach area. How many calories do I need to consume to lose weight?

Answer:

The number of calories needed to lose weight is dependent on many factors.  You are correct in listing your age, weight and height.  These are important factors, but your metabolic rate, the efficiency by which you burn calories, is dependent on other factors as well.  Your actual metabolic rate (calories you need to maintain your weight currently) is the sum of the calories you need for your current level of exercise (this ranges from 0 to 15% of your total calorie need) plus the calories needed to perform your normal daily activities (25% of your total calorie need) and your resting metabolic rate (60-75% of your total calorie need).  Knowing your RMR (resting metabolic rate) is a key factor in answering your question.

The RMR is dependent on the factors you listed plus gender, body composition, genetics, hormones, medications and disease states.  A person with a greater percentage of his/her weight that is muscle will have a higher RMR than someone who has a greater percentage as fat.  Your RMR can be determined through a test which measures how much oxygen your body needs at rest when you are fasting, rested, and have followed a few other requirements.  The oxygen your body needs at rest is an indirect measure of how efficiently your body burns carbohydrates, fats and protein.  These tests are often available through medical fitness facilities and hospitals and may be covered by your insurance.

This is a very long answer to your question.  There are equations that can estimate your calorie needs, but they would require knowing your gender.  Often the equations overestimate calorie needs for individuals who are overweight.  Once you know your body's calorie needs, aim to reduce your calories and increase your activity to accomplish a 500-1000 calorie deficit per day.  Most people will experience a 1/2 to 1# weight loss per week with daily deficits in this range.

Thank you for your question.

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Response by:

Shirley A Kindrick, PhD Shirley A Kindrick, PhD
Team Leader of Comprehensive Weight Management
College of Medicine
The Ohio State University