Cutting calories is the approach most dieters must take to meet their weight-loss goals. But every once in a while people take calorie restriction too far, ultimately making weight loss slower and more difficult by slowing your metabolism.
Figuring out the right number of calories for you on a daily basis depends on your age, gender, and activity level. In general, the younger and more active you are, the more calories you can consume. And men are able to eat more calories daily than women. For example, the U.S. Department of Agriculture guidelines says that women 19 to 30 years old should consume 2,000 calories if they have a sedentary lifestyle or 2,400 calories if they have an active one; for men of the same age the range is 2,400 to 3,000 calories.
Defining the Low-Calorie Diet
It seems logical that if calories are the problem, you would want to eat as few of them as possible to speed weight loss. As a general rule, people need a minimum of 1,200 calories daily to stay healthy. People who have a strenuous fitness routine or perform many daily activities need more calories. If you have reduced your calorie intake below 1,200 calories a day, you could be hurting your body in addition to your weight-loss plans.
“The big picture is to consume enough calories with a balance of nutrients and engage in physical activity for good health management to achieve one’s weight goals. Consuming less than 1,200 calories per day may make it difficult to meet vitamin and mineral needs via food,” says nutrition therapist Andrea Spivack, MA, RD, LDN, with Penn Behavioral Health at the University of Pennsylvania in Philadelphia.
Tempting as it may be to continue with your low-calorie weight-loss plan and simply take a supplement, Spivack points out that there are some key nutrients which are only available through your diet.
Occasionally, obese people will go on a very low-calorie diet — 800 to 1,000 calories per day — for a brief period of time in order to achieve a specific weight-loss goal, but then will switch to a diet with more calories to reach and maintain their desired weight. Such a diet is usually supervised by a doctor or nutritionist so that it is nutritionally balanced. Unfortunately, weight regain is common after these restricted calorie diets end.
Why Low-Calorie Diets Slow Your Metabolism
If you are on a very low-calorie diet, you may wonder why the numbers on your scale aren’t budging, but your diet buddy is slimmer by the month.
The reality is that different people respond differently to low-calorie diets. When your body senses that food may not be in plentiful supply, it may slow down your metabolism as protection against the possibility of starvation, even if you are obese and deliberately trying to lose weight.
“In some people, the metabolic rate [how fast the body burns calories] is only slightly reduced to make up the shortfall in energy difference, while in others it is far greater. It is this variability in the metabolic rate with energy restriction that causes much of the variability in weight loss between people,” explains Leanne M. Redman, PhD, an instructor of human physiology at the Pennington Biomedical Research Center in Baton Rouge, La. Redman and colleagues have been studying the impact of very low-calorie diets on weight loss and other measures of health.
Calories: Are You Getting Enough?
Here are signs that you are not getting enough calories:
You can use online tools, such as My Calorie Counter, to help you track your daily calorie intake. MCC allows you to set a target for daily calorie consumption and can tell you throughout the day how you are doing.
If you are still interested in a low-calorie diet, consult a doctor or dietitian who can help you create a nutritionally balanced diet that won’t leave you hungry and frustrated.