If you are in your 30's, 40's or beyond, you have no doubt figured out that no matter how much you diet and deprive yourself of food...no matter how many miles you log on the treadmill..and not matter how good you are, losing weight after a certain age is definitely harder than it is when you were in your 20's. But did you ever wonder why? In this hub, I am going to explain the science of weight loss and why dropping weight after 40 is so difficult.

We are also going to go over some ways to deter this and actually get your body to work with you again and not against you.

As our bodies age, everything in it starts to get older and doesn't work as well. I am sure that if you are over 40 then chances are good that your eyes don't work as well in dim lit rooms as when you were much younger. The same goes for what inside your body as well. What we need to do is restore a few key components in your body to make it work like when you were 20.

Losing weight has a lot to do with insulin....

As we age, most of us start to become more resistant to insulin. This isn't a good thing if you want to lose weight. When you become insulin resistant, it impairs the ability of cells to efficiently take up glucose and utilize it for energy. In plain english, what you get is excess insulin and this is not a good thing.

To restore your insulin levels back to days of your youth, all you simply need to do is eat less. A calorie restriction of 1,500-1,800 calories a day will dramatically enhance insulin sensitivity.

There are some natural nutrients that you should add to your diet to help restore insulin sensitivity. Chromium, Magnesium, fish oil, and cocoa polyphenols (what you find in dark chocolate) are all great supplements that will work with insulin production

To Lose Weight, we need to increase our caloric expenditure even when we are doing nothing....

Another HUGE problem that we face as we age when it comes to weight loss is that our resting metabolic rate drops.  What is a resting metabolic rate?  Our bodies are at work even when we aren't.  When we eat, we burn calories, when we sleep we burn calories.  When we watch TV, we burn calories.  The question is what is the difference between when we were young and as we age, right?

Scientists and researchers have found that this energy expenditure in older adults may cause an excess of 120-190 calories to be stored in our body every day.  While this number probably won't jump out at you, consider this.  In layman's terms, this little calorie addition would cause an extra 13-20 pounds of body fat.

The good news is there are ways to increase your resting metabolic expenditure rate.  The most well known is to drink green tea.  Researchers have found that green tea polyphenols when taken in combination with caffeine actually enhance thermogenesis.

Another methods to help increase REER is to take a fish oil caplet rich in EPA and DHA.  While a lot of people understand the positive effects of fish oil on the body (it has anti-inflammatory properties), the omega 3 fatty acids work well to boost thermogenesis.

Finally, believe it or not, hot peppers..aka capsaicin, have been shown to help enhance energy metabolism in humans.  Studies have found that red pepper increases core body temperature and your metabolic rate, which will go a long way to helping you lose weight.

Tryptophan...you know...the stuff that makes you sleepy after you have thanksgiving turkey...can be something that is key to weight loss.  The reason?  Serotonin affects how full you feel and how satisfied you are are.  In other words, a serotonin deficiency could be associated with carbohydrate binging and carbohydrate binging could lead to the accumulation of excess body fat.

Tryptophan is needed to produce serotonin in the body.  People who are obese or overweight have lower blood tryptophan levels.  The real issue here is inflammation on the cellular level.  Inflammatory cytokines are made and released in body fat.  An enzyme in turn is activated which actually degrades tryptophan in the body.

And here is the real problem-  According to a case study in the American Journal of Clinical Nutrition, obese patients have decreased levels of tryptophan that actually remains low even with weight loss and proper diet.  It is a slipper slope for those who want to lose weight after 40....

The tryptophan reduces serotonin.  As a result, satiety is impaired and this contributes to increased caloric consumption.

The good news is that pharmaceutical grade tryptophan is available to Americans after 19 years of restrictions.