To lose weight you need to burn off more calories than you take in, but fast weight loss usually doesn't produce long-term results. Losing a pound or two a week is the safest and most effective strategy, say the experts at MayoClinic.com. The number of calories you need to consume to lose weight depends on your age, sex, current weight and activity level. Always talk to a health care provider before starting a weight loss plan.
Function
You need to determine your basic calorie needs before you can create a calorie deficit that results in weight loss. One of the most common formulas for this is called the Mifflin formula, after M.D. Mifflin, lead author for a calorie-need-prediction study published in the 1990 "American Journal of Clinical Nutrition." If you are a man, use this formula: 9.99 times weight plus 6.25 times height minus 4.92 times age plus 5, or (10 x w) + (6.25 x h) - (5 x a) + 5. If you are a woman, use this one: 9.99 times weight plus 6.25 times height minus 4.92 times age minus 161, or (10 x w) + (6.25 x h) - (5 x a) -- 161.
You need to convert your weight into kilograms and height into centimeters to utilize this formula. Multiply inches by 2.54 to get the centimeters. Multiply pounds by 0.45359237 to get kilograms. The result you get is called your resting metabolic rate.
Considerations
You need to do another calculation to get a handle on your daily calorie needs, because your activity level affects how many calories you can consume without gaining weight. Find the estimated number of daily calories that will keep you at your current weight by picking an activity factor and multiplying it by your resting metabolic rate. Factors are: 1.2 for sedentary, 1.375 for light exercise one to three days a week, 1.55 for moderate level exercise three to five days a week, 1.725 for hard exercise six to seven days weekly, and 1.9 for hard daily exercise as well as having a physical job.
Prevention/Solution
To lose weight, change your food intake so you are consuming 500 calories a day below what you need to maintain your current weight, advises Lori Bicek, a dietitian, personal trainer and exercise physiologist writing for Eat Right Illinois. If you are overweight or moderately obese, this will lead to about a pound of weight loss each week. If you are obese, you can create a calorie deficit of 750 to 1000 calories to shed up to 2 lbs. a week, though this needs to be done under a doctor's supervision. As you lose weight or increase activity remember to recalculate your daily calorie needs. A pound of fat has 3500 calories.
Warning
Don't overly restrict calories if you want to lose weight effectively. You must take in a certain amount of calories to promote healthy weight loss. In fact, it actually takes calories to burn calories, Bicek said. If you cut calories too drastically, you train your body to use fewer calories because it goes into starvation mode. In this mode, your basal metabolic rate, or the rate at which your body burns calories to gain energy, drops. A better goal is to train our body to use more calories instead of fewer calories, which can be achieved via diet and exercise, Bicek advises.
Expert Insight
Remember that weight loss is a balancing act that comes down to burning more calories that you consume, advises MayoClinic.com. Cutting extra calories and increasing calorie burn via physical activity are both important components, say the experts at the clinic. Gaining a support network made up of family, friends and medical care providers also is an important component. Planning for setbacks is a good idea, too, because it will help you overcome them.
References
- Illinois Dietetic Association: I Eat Right and Exercise---Why Can't I Lose Weight?; Lori Bicek, Dietitian . Personal Trainer, Exercise Physiologist; Illinois
- "American Journal of Clinical Nutrition"; A New Predictive Equation for Resting Energy Expenditure in Healthy Individuals; M.D. Mifflin et al.; 1990
- MayoClinic.com: Weight Loss Basics
- MayoClinic.com: Fast Weight Loss---What's Wrong With It?
- American Council on Exercise: Harris-Benedict Equation
- Calories Per Hour: Calculating BMR and RMR
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