The problem with simply dieting is that you lose muscle as well as losing fat. Muscle tissue is what ups your metabolism to help you burn those calories. So unless you are also doing something like weightlifting to maintain and increase your muscle mass, you are usually fighting a losing battle. The other thing is that, for the same volume, muscle weighs more that fat. So you may not think you are losing that much weight on the scale, but if you are actually building lean muscle, you are going to be much leaner even if there is not necessarily that much weight loss.
You might find this site interesting:
http://eatmore2weighless.com/
Certain people find that their body easily switches into a sort of starvation mode and reduces metabolism if they don’t eat enough calories. That site has some people who are eating twice as many calories (good foods, of course not junk) and working out and they lose alot of fat.
Testosterone plays a critical role in maintaining lean body mass. Peak testosterone production takes place in deep sleep. I’m a big proponent of targeting a solid eight hours of sleep a night. It can take about as much self-discipline as a regular exercise routine, but IMHO, plays a big role (and as an aside, I’m 46 with the same waist size I had when I was 20: 32-34”).
As men get into their late 30s and 40’s not only does the natural testosterone level decrease, but the body increases levels of some female hormones. Saw Palmetto, best known for its prostate maintenance effects, will also bind and inhibit some of the female hormones that would otherwise bind to the natural testosterone.
I also avoid soy at all costs as it will mimic estrogen in the male body.
I try to walk at least five miles a day (briskly) which is easy for me to do as I work in Manhattan and even on the inclement days, I can walk the underground tunnels of Grand Central - which is right by my office. I'm trying to avoid the weight room as I like being out in the fresh air.