DEAR DR. ROACH: When we exercise on a stationary bike, treadmill, stair stepper, etc., many of the machines show the number of calories burned during our workout. Are the calories that are shown gross or net? For example, if the machine indicates 280 calories after an hour, is that in addition to the approximately 80-120 calories (my guess) the body uses every hour for us to live, or is the 280 calories include the 80-120 calories? We may be deceiving ourselves about our workout and how much we can eat if it is the latter. I’ve asked many people who exercise as well as those who work at health clubs, and no one seem to know. — V.F.

ANSWER: I believe that in most cases the number is intended to show the net calories, the ones expended in exercise over and above the amount of calories we expend on basal metabolism (which is closer to 50 calories an hour for most people). However, the machines provide only a rough estimate, with a potential for error that is pretty large. To measure accurately, the machine needs to know your body weight and heart rate, and ideally should know your VO2, a measurement of how much oxygen you consume at your peak exercise. This is obtainable by a stress test with gas exchange, something few people (but many elite athletes) have done. Some newer machines at the gym allow users to enter in this information, and some smart watches will then give you both ”active calories” and ”total calories.”

I think many of us deceive ourselves in all kinds of ways about exercise and diet. We overestimate our exercise, and I still see people who feel that some calories consumed don’t ”count.” But the fact remains that a 2-mile run burns less calories than are contained in many energy bars.

If you are exercising more in order to maintain weight, the best measurement is your weight. If it’s higher than you want, you need to eat less, exercise more or do both.

DEAR DR. ROACH: How much does dietary cholesterol have to do with cholesterol in the body? Are eggs as bad as some people think? Or does the body make enough cholesterol itself, that dietary cholesterol really doesn’t make much difference? — J.S.

ANSWER: You are right that the cholesterol in the blood can come either from eating cholesterol (found only in animal products) or by the body making its own (in the liver). Eggs are modestly high in cholesterol; organ meats, such as brain and liver, are even higher in cholesterol. However, the scientific consensus is that dietary cholesterol is not a major risk factor for development of heart and other vascular disease. One egg a day does not seem to increase (and may decrease) risk of heart disease in healthy individuals. The amount of cholesterol your body makes goes down if you consume more, to a point. Also, eggs have other necessary nutrients and are more filling for most people than an equivalent amount of carbohydrates, such as cereal or oatmeal.

However, this doesn’t mean that large amounts of cholesterol are always OK. Many high-cholesterol foods also are high in saturated fat, which is much more clearly linked to heart disease.

I believe that paying more attention to sugar and refined carbohydrate intake, and less to cholesterol, will improve overall health.

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Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or request an order form of available health newsletters at 628 Virginia Dr., Orlando, FL 32803. Health newsletters may be ordered from www.rbmamall.com.

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