The Hamwi Approach to Determining Your Optimum Weight


measuring waist

Dr. GJ Hamwi's formulas for calculating an individual's ideal weight are derived from the belief that a woman that is exactly 5 feet tall should weigh 100 pounds, and that a man that is exactly 5 feet tall should weigh 106 pounds. Hamwi's formulas first appeared in a publication of the American Diabetes Association in 1964, and are currently supported by many medical practitioners and nutritionists throughout the world.

One concern with the accuracy of the Hamwi approach to determining your optimum weight is that an individual's lean muscle mass is not taken into account. This may produce a result that underestimates the optimum weight for an individual.

For example, since muscle, by volume, weighs more than fat, an individual that regularly weight trains may have an increased level of lean muscle mass, and hence, weigh more than the recommended amount calculated through the Hamwi approach. While the individual may have a high level of lean muscle mass, they may also have a low percentage of body fat as well.

In this case, it would be advised that the individual simply use common sense when determining their optimum weight. 

Calculate your Optimum Weight Using the Dr. GJ  Hamwi Approach


  • For Women: The ideal weight for a woman who is exactly 5 feet tall is 100 pounds. For every additional inch above 5 feet, add five pounds. If you are shorter than 5 feet tall, subtract five pounds for every inch you measure below 5 feet.

    Next, you will need to determine whether you have a small, medium or large frame. Using a measuring tape, measure your wrist. If your wrist measures exactly 6 inches you have a medium frame, and the ideal weight number you calculated above does not need to be adjusted. If your wrist measures less than 6 inches, then subtract 10% from your ideal weight number. If your wrist measures more than 6 inches, then add 10% to your ideal weight number.

  • For Men: The ideal weight for a man who is exactly 5 feet tall is 106 pounds. For every additional inch above 5 feet, add 6 pounds. To determine whether you have a small, medium or large frame, you will need to measure your wrist. If your wrist measures exactly 7 inches, you have a medium frame and you do not need to adjust your ideal weight number. If your wrist is smaller than 7 inches, you have a small frame and will need to subtract 10% from your ideal weight number. If your wrist is larger than 7 inches, you have a large frame and will need to add 10% to your ideal weight number.

Determine Daily Caloric and Fat Intake


Now that you have calculated your ideal body weight, it's time to determine the number of calories your body requires per day. In order to accurately do so, we will first need to take into account your level of physical activity.

  • If you are completely inactive and do not exercise, multiply your adjusted ideal weight by 11.

  • If you regularly exercise two to three times per week, multiply your adjusted ideal weight by 13.

  • If you regularly exercise four to five times a week, multiple your adjusted ideal weight by 15.

  • Finally, if you regularly exercise six to seven times a week, multiply your adjusted ideal weight by 18.

The number that you just calculated is the number of calories that your body requires on a daily basis.

At this point, you have determined your ideal weight and the total number of calories that your body requires per day. Next, you will want to determine the percentage of your total calories that can come from fat.  Most medical professionals and nutritionists recommend that you limit your daily intake of fat to 30% of your total calories. However, if you are seeking to lose weight or have a history of heart disease or cancer, it's better to limit your daily fat intake to 20% of your total calories.

An Example


The following example can be used as a guide to the Hamwi approach of determining your ideal weight. The example pertains to a woman that is 5 foot 4 inches tall and has a large frame. She currently weighs 150 pounds and regularly exercises two to three times a week.

Ideal weight: 100 pounds (woman 5 feet tall) + 20 pounds (add 5 pounds for every inch over 5 feet) X 10% (large frame) = 132 pounds


Daily Caloric Intake: 132 pounds (ideal weight) X 13 (exercises 2-3 times per week) = 1,716 calories per day


Weekly Caloric Intake: 1,716 (calories per day) X 7 (number of days in a week) = 12,012 calories per week

Adjusting the Plan for Weight Loss


She is on a weight loss program, so she will want to limit her fat calories to about 20% of her total daily caloric intake.

Number of allowable calories from fat: 1,716 (calories per day) X 0.20 (20% allowable fat) = 343.2 calories per day from fat

Next, we will want to convert the fat calories into fat grams as this will make it easier to read the food labels and plan your meals. One gram of fat equals 9 calories.

Number of grams of allowable fat per day: 343.20 (allowable calories from fat) / 9 (calories in 1 gram of fat) = 38.13 grams of fat per day

Since our sample woman is overweight (currently weighing 150 pounds) and is going to start a weight loss program, in order for her to lose 1 pound of body weight per week she will need to eliminate 3,500 calories from her weekly caloric intake. Next, we will want to calculate our subject's adjusted weekly caloric intake, per week, to support her weight loss goal.

Adjusted weekly caloric intake: 12,012 (total calories per week) – 3500 (calories needed to lose 1 pound) = 8,512 calories per week


Adjusted daily caloric intake: 8,512 (adjusted total calories per week) / 7 (number of days in a week) = 1,216 calories per day


In this example, our subject woman could simply decrease her daily caloric intake from 1,716 calories per day to 1,216 calories per day in order to lose 1 pound per week. Furthermore, she would achieve her weight loss goal of obtaining her ideal weight of 132 pounds in 18 weeks.

woman on scale

An alternative (and ultimately more advisable) approach to achieving her weight loss goals in a shorter period of time would be to increase her weekly level of aerobic activity.

By doing so, she would burn more calories per day, and coupled with her decrease in daily caloric intake, obtain her weight loss goal in a shorter timeframe.

For many individuals, it can be difficult to maintain proper nutrition while consuming only 1,200 calories per day. For this reason, our subject female could adhere to a more reasonable caloric intake plan (1,500 calories per day, for example).

Under this caloric intake scenario, she could then begin an exercise routine in parallel with her nutritional diet of 1,500 calories per day and still maintain the same overall daily caloric deficit.

To compensate, she would need to burn an additional 300 calories per day in order to complete her weight loss goal in the aforementioned timeframe of 18 weeks.