As mentioned in a previous post the shift in fitness lately has been towards lifting large, heavy weights for 6-8 repetitions with rest in between each set. This type of training in nature will cause damage to the muscle fibres and promote growth or size of the muscle (if the body is providing the right nutrients but I will get to that in another post). The demands made on the muscle and the results achieved can be quite significant and can cause a shift in size of the muscle to a much larger mass. This will be greater in men (due to increased natural levels of testosterone) but also in women.
To maintain larger muscle mass the body would require more fuel to run effectively if continued heavy lifting is performed in their training sessions. These sessions would cause much muscle fibre damage therefore stimulate hunger to replenish lost muscle from training. Hormone levels would also play a major role in regulating appetite.
The two main hormones that control appetite are Ghrelin and peptide YY. Ghrelin is known to increase appetite and peptide YY is known to decrease it. The New York Times reported on a study of females runners and found that after exercising the runners ate less than those who walked or were sedentary. The concluded it was a rise in peptide YY that regulate hunger and a drop in Ghrelin. They also studied people who were exercising regularly and also found that they were better able to regulate their hunger throughout the day than those who didn’t. These results were only in people who exercised regularly for several months. It seems the appetite suppressant quality of exercise only works in long term exercisers. A study by UK Universities in Sheffield, Hallam and Loughborough into weight training vs. cardio vs. sedentary lifestyles has found that cardiovascular exercise decreases hunger by acting on both Ghrelin and peptide YY but weight training only acts on Ghrelin, causing only minimal effects to appetite after training. This combined with the muscle loist during training would surely increase appetite after heavy lifting.
Much research has been done lately into metabolic rates in obese people and the conclusion the Mayo Clinic (well known clinic in America) came to is that large or obese people actually have a faster not slower metabolic rate than smaller slimmer people. Seems that argument that people make about having a “slow metabolism” causing them to put on weight is now gone! Looking at the other end of the spectrum most runners, or those people who perform intense cardiovascular type exercise have less fat and would require less energy thus decreasing their appetite. I know in myself that after I have been for a run the last thing I feel like is eating!
So the moral to the story here is to try a combination of exercise, resistance consisting of smaller weights with more repetitions (I like 15-20) and include cardiovascular exercise in your routine if you want to lose bodyfat and control your appetite.