The Effects of Consuming Too Few Calories on Your Metabolism

Are you diligent with your diet and exercise program but still not losing weight? It’s possible that you are a little too diligent! Most of you have probably heard that eating too few calories can slow your metabolism, thereby making weight loss more difficult. This is true. Studies have shown that your body can slow its metabolism by as much as 30% when you undereat.

What is “undereating”?
This will depend upon your age, sex, weight, height, activity level as well your individual metabolism. For the average woman, consuming fewer than 1200 calories would be too low. The fewer calories you consume, the greater the impact on your metabolism. Consuming 800 calories or less on a daily basis has the greatest effect of slowing your metabolism. Not only does consuming too few calories slow your metabolism while you are dieting, it will also cause your metabolism to stay in “slow-down” mode for a period of time even after you go off the strict diet. This contributes to weight regain.

Typical sceniero
Let’s say you want to drop 20 pounds somewhat quickly for a special occasion – so you follow a strict 1000 calorie diet. You initially lose 10 pounds  in the first month, however your weight plateaus for the next two months. The scale doesn’t budge. You get frustrated and go off the diet and revert back to your old eating habits (which weren’t so bad to start with!) and find yourself regaining the weight you lost. In the past, your eating habits maintained your weight. The fact that you are now gaining has to do with the fact that your metabolism has slowed from strict dieting.

How can you increase your metabolism from eating too few calories?
1. Continue to exercise regularly. This will help to rev up your metabolism. Weight training is especially important to build muscle mass. The more muscle you have, the faster your metabolism will be. However, this does not mean you should “over-exercise”.  Exercising too much, along with undereating, will slow your metabolism even more!

2. Slowly increase your caloric intake. This will help to speed your metabolism. Everyone is different, however I have found that many of my clients do well with increasing their calories by approximately 100-200 a month. So for example, if you are currently consuming 800 calories a day, get up to 900 for 2 weeks or so, then increase to 1000. This will give your body time to adjust to the higher caloric intake without causing weight gain. Your eventual goal will likely be a minimum of 1200-1500 calories a day. Make sure you are adding in calories in a balanced manner – protein, fat and healthy carbs.  Continue to exercise as you are increasing the calories, however don’t increase your exercise. This will only offset your increased caloric intake.

Very few people actually consume too few calories!
I frequently have people come into my office claiming they hardly eat anything and are still not able to lose weight. In my experience, once these people keep a food record for a few weeks, they find they are actually eating more than they think. However, there are definitely some people who are eating too few calories. I would recommend you keep a food record for a week or two to see which category you fit into.

Bottom line, while we all have days where we might consume too few calories, doing so on a regular basis is self-defeating as it will only slow your weight loss and make weight gain more likely once you have gone back to your normal eating patterns. The best way to lose weight is to follow a moderate calorie restricted diet and engage in a regular exercise program that includes weight training and cardiovascular exercise.