Exercise and Appetite

Exercise Suppresses Appetite By Affecting Appetite Hormones   

ScienceDaily (Dec. 19, 2008) — A vigorous 60-       minute workout on a treadmill affects the release of two key appetite hormones, ghrelin and peptide YY, while 90 minutes of weight lifting affects the level of only ghrelin, according to a new study. Taken together, the research shows that aerobic exercise is better at suppressing appetite than non-aerobic exercise and provides a possible explanation for 

how that happens.

Treadmill versus weight lifting                                            

There are several hormones that help regulate appetite, but the researchers looked at two of the major ones, ghrelin and peptide YY. Ghrelin is the only hormone known to stimulate appetite. Peptide YY suppresses appetite.

Ghrelin was discovered by researchers in Japan only about 10 years ago and was originally identified for its role as a growth hormone. Only later did its role in stimulating appetite become known. Peptide YY was discovered less than 25 years ago.

In this experiment, 11 male university students did three eight-hour sessions. During one session they ran for 60 minutes on a treadmill, and then rested for seven hours. During another session they did 90 minutes of weight lifting, and then rested for six hours and 30 minutes. During another session, the participants did not exercise at all.

During each of the sessions, the participants filled out surveys in which they rated how hungry they felt at various points. They also received two meals during each session. The researchers measured ghrelin and peptide YY levels at multiple points along the way.

They found that the treadmill (aerobic) session caused ghrelin levels to drop and peptide YY levels to increase, indicating the hormones were suppressing appetite. However, a weight-lifting (non-aerobic) session produced a mixed result. Ghrelin levels dropped, indicating appetite suppression, but peptide YY levels did not change significantly.

Based on the hunger ratings the participants filled out, both aerobic and resistance exercise suppressed hunger, but aerobic exercise produced a greater suppression of hunger. The changes the researchers observed were short term for both types of exercise, lasting about two hours, including the time spent exercising, Stensel reported.

“The finding that hunger is suppressed during and immediately after vigorous treadmill running is consistent with previous studies indicating that strenuous aerobic exercise transiently suppresses appetite,” Stensel said. “The findings suggest a similar, although slightly attenuated response, for weight lifting exercise.”  

Focus on active ghrelin

Previous studies have been inconclusive about whether exercise decreases ghrelin levels, but this study may help explain those mixed results, according to the researchers.

Ghrelin comes in two forms, acylated and non-acylated. The researchers measured acylated ghrelin, also called active ghrelin, because it can cross the blood-brain barrier and reach the appetite center in the brain. Stensel suggests that future research concentrate on active ghrelin.

While the study showed that exercise suppresses appetite hormones, the next step is to establish whether this change actually causes the suppression of eating

Physical Exercise

There is no age or condition to start making (or resume) of exercise. Although exercise alone, without eating a healthy and appropriate, can not burn fat effectively, you must consider when you want to burn fat and lose weight. Indeed, a healthy diet and regular exercise should go together to burn fat.

Physical exercise

Physical exercise can help you burn fat because:

1) Exercise regulates appetite
Although some people think that exercise increases appetite, so that the food consumed will cancel the number of calories burned during exercise, this is not the case. In fact, exercise regulates your appetite helping you eat fewer calories. And eating fewer calories can help burn fat.

2) Exercise increases metabolism
Another misconception is thinking that exercise is not worth the effort because of the relatively low number of calories used.

For example, walking burns about five calories per minute. Since there are 4,000 calories in 500 grams of fat, you might think you have to walk more than 13 hours to lose 500 grams of fat. But the truth is that even when you’re exercising at a moderate pace, you increase your metabolic rate by 8 (to burn calories) for hours after the end of the year. This residual effect, not the exercise itself, is the biggest gains that would accrue to the fact of physical exercise to burn calories and fat.

3) Physical exercise keeps the muscles
The movements included in your exercises require you to use your muscles, causing physiological changes so that the muscles maintain (even increase) their size and power.

Since every pound of muscle requires 100 to 200 calories per day to maintain and that fat is burned almost exclusively in the muscles, maintain your muscles is essential for losing body fat. Without physical exercise, you lose muscle and reduce your ability to burn fat. When it comes to your muscles, you can either use them or lose them.

4) Physical exercise increases the number of fat-burning enzymes
Muscles have very specific enzymes which burn only fat. Studies have shown that people who exercise regularly have significantly more fat-burning enzymes in their muscles than people who do not exercise.

In other words, exercise pushes your body to “enhance” its ability to burn fat more efficiently. This means that the more you use your muscles with exercise, your muscles develop more enzymes fat-burning.