Asked by Angelica Kelly, Dublin, Ohio
Is it true that when your metabolism slows down (e.g. from exercise, age, etc.), adding calories proportionally will "kick-start" it back to prior fat-burning levels? In my case, my rate slowed from 2,000 to 1,500, and the gym's nutritionist recommended an increase in calories from 1,600 to 1,900. Thank you.
Diet and Fitness Expert
Dr. Melina Jampolis
Physician Nutrition Specialist
This is a great question as metabolism is a big source of confusion for many people. Before I answer your question, let me clarify that while metabolism does drop with age (about 3 percent per decade) due to muscle loss and hormonal changes, it does not drop with exercise, but rather increases due to direct calorie burning during your workouts and indirectly through an increase in muscle mass as a result of your workouts. I'm not sure how your metabolism was tested (it can be tested directly by a breathing test, which is available in some gyms and doctors' offices, or it can be calculated using several different formulas), so the significant drop that you report may not be completely accurate.
What could cause a big drop in your metabolism? If you lost a lot of weight, your metabolism could drop because you simply need fewer calories because of your smaller size. If you lost weight very quickly by significantly undereating (undereating would be considered less than 1,200 calories, which it does not sound like you did if you were eating 1,600 calories per day), you might see a temporary drop in metabolism, and this could respond to a moderate increase in calories, but I don't think that's the case for you. And finally, a medical condition such as underactive thyroid could cause a significant drop in metabolism, so if you have noticed increased fatigue, hair loss, constipation, weight gain or dry skin, you may want to talk to your doctor about getting a simple blood test to make sure that your thyroid is not underactive.
In any case, if your metabolism dropped, I would recommend dropping caloric intake slightly (but don't go below 1,200 calories) instead of increasing daily caloric intake. And to optimize metabolism, make sure that you eat at least three meals per day. (I also like to see at least one snack -- usually in the afternoon between 3 and 5 p.m.) I also recommend changing the ratios of nutrients in your diet to optimize metabolism. This can be done by increasing protein slightly and decreasing either carbohydrates or fat. In addition, make sure that you drink plenty of water, as being even 1 percent dehydrated can drop metabolism significantly. Finally, you might want to consider boosting your strength training routine to increase muscle mass which, over time, can increase (or maintain) metabolism.
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