Exercise & Appetite

It’s unfair but true. Men have an easier time losing weight than women do. Scientists think it could be because women’s fat cells are more prone to storing fat. A new study may have discovered another reason. Exercise may stimulate a woman’s appetite so she ends up eating an equal amount of calories or more than she burns in the workout.

In the past, research on rats found that male rats do not increase their caloric intake in response to exercise and consequently lose weight. Female rats eat more after exercising and maintain their weight.

It turns out that when it comes to exercise and appetite, humans may be just like rats. Many studies have shown that moderate and high intensity exercise have no effect on a man’s appetite. Last year, a Canadian study at the University of Ottawa found female participants consumed more calories at lunch after they exercised vigorously in the morning compared to when they exercised at a low intensity or not at all.

The researchers defined “high intensity” as walking at a fast pace for 37 minutes on a treadmill (70% of peak oxygen uptake) while “low intensity” (40% of peak oxygen uptake) was defined as walking at a slow pace for 65 minutes. The duration of the workouts were adjusted so that everyone was burning 350 calories per session.

Does this mean that it’s better not to exercise or not to exercise vigorously if you want to lose weight? Not at all. The Canadian study found that the women ate 878 calories during lunch after a high intensity workout, 819 calories after low intensity exercise, and 751 calories when they did not exercise.

Although they ate the fewest calories at lunch on the day they did not exercise, when analyzed in the context of their total calories in and calories out for the whole day, they actually consumed more net calories.

So if you want to lose weight, it’s still better to exercise than sit on the couch. A 2002 study found that fit menopausal women only had 25% body fat compared to sedentary menopausal women who had 38% body fat.

You burn more total fat calories during vigorous workouts compared to lower intensity exercise. As long as you control what and how much you eat after such workouts, you will still be a winner in the weight loss game. So if you enjoy vigorous exercise, go ahead.

A 1990 study on 1,366 women and 1,257 men suggested that those who did high-intensity exercise tended to have less body fat than those who did lower-intensity workouts.

For those who cannot control their appetite, low intensity-longer duration exercise of any kind may be more appropriate for you.

Appetite is temporarily suppressed immediately after exercise but ravenous hunger can come upon you 1 to 2 hours after. Take advantage of that small “window of opportunity” to head off your appetite. Eat a small snack within thirty minutes after working out if you are not ready to eat a main meal. The snack should be about 100
-150 calories and should contain protein and carbohydrates. A glass of milk is an example. The protein helps to suppress your appetite while the carbohydrates help restore glycogen (a storage form of carbohydrates in the muscles) that was used during the workout.

Do not exercise hungry because you will be very hungry after. For example, if you exercise at 5:00 p.m. and the last time you ate was at lunch, don’t be surprised if you lose control of your appetite at dinner.

Watch out for psychological hunger. It’s that attitude that says, “I deserve to eat as much as I want because I had a hard workout”. You are probably not burning as many calories as you think you are. In a 2004 University of Alabama study, normal weight women overestimated the amount of physical activity they did in one day (formal exercise plus activities of daily living) by 600 calories. Overweight women overestimated it by 900 calories.

Aside from gender, appetite after exercise is also affected by temperature.

Scientists have long suspected that swimming in cold water increases the appetite compared to exercise like jogging or cycling, which makes one feel hot and sweaty after. Some studies have also found that swimming is not as effective for weight loss as land-based exercise.

Jaci Van Heest, exercise physiologist of the United States Swimming Association, has stated that although elite swimmers and runners burn approximately the same calories while training, top swimmers have 3 to 5 percent more body fat than top runners do.

In a study published this year, researchers at the University of Florida have confirmed that there is indeed a connection between cold-water exercise and appetite.

They compared the energy used and the calories consumed after riding a stationary bike submerged in cold water (68 degrees F) and warm water (91.4 degrees). The participants burned 517 calories in cold water and consumed 877 calories after. When they exercised in warm water, they burned 505 calories and consumed 608 calories after.

So that’s why scuba diving could open up my appetite like no other activity could.

The take home message is that exercise does not guarantee weight loss if you will overcompensate for the calories burned. That goes for both men and women. A study last year illustrates that less is sometimes more. Male participants did either one set or three sets of upper body weight lifting exercises for two months. Both groups became 21% stronger but the group that lifted only one set had a greater fat loss (19%) than the group that did three sets (10%). Calorie overcompensation was the suspected reason.

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