By SUSAN CALLAHAN, Associate Editor and Featured Columnist
The more scientists study weight loss, the more we learn that we are not really human. We are instead a walking chemistry experiment, whose equations have been negotiated by evolution. Okay, I am overstating.
What I mean is that, if we think of being "human" as the ultimate expression of a being with free will, capable of influencing his or her pathway in life, then that description seems less and less to fit us. When it comes to weight loss, chemistry really does matter more than willpower.
The latest important discovery is a hormone called "irisin". Irisin was identified in 2012 by scientists from Harvard Medical School. Dr. Bruce Spiegelman and his research team conducted a set of experiments on mice. They found that mice which exercised released a hormone that triggered the release of fat from fat cells. That hormone is irisin.
Irisin Unlocks the Fat from Storage Cells
When you eat more than you burn in exercise, the body stores the extra calories as fat. The fat is stored in white fat cells. Irisin circulates in your blood stream, visiting the storage cells where fat is stored, opens the storages, and allows fat to be released so that your body can use it as energy.
A single session of intense strength training or endurance exercise is all it takes to elevate your irisin levels.
That was the finding in a 2015 study from researchers at Lillehammer University in Norway. That study looked at the effects on irisin levels in nine healthy participants. Over a three week period, the group was put through periods where they had to do an hour of intensive exercise, strength training or no exercise at all.
Blood levels of irisin were measured after the sessions. What the scientists found was irisin levels rose after any form of intense exercise, whether it was strength training or endurance exercise. But the amount of time it took for the irisin levels to rise was different.
With endurance exercising, your irisin levels rise immediately.
With intense strength training, your irisin levels rise after one hour.
With both types of exercise, your irisin levels gradually return to a normal baseline.
What this means is that you lose fat whether you do endurance exercise or strength training. The loss with endurance exercise is immediate and the loss with strength exercise occurs within an hour after you stop exercising.
Where Does Fat Go When You Lose Weight?
When you exercise, irisin unlocks the storage bins so that fat cells can release the fat your muscles need to work. But where does this fat go?
Scientists from Australia have answered this question.
Fat molecules are made up of carbon (55 atoms), hydrogen (104 atoms) and oxygen (6 atoms). As you can see, there are relatively few oxygen atoms in fat. When you add oxygen to a fat molecule by exercising, the chemical reaction produces carbon dioxide plus water.
This means that the more you exercise, the more fat is mixed with oxygen to produce carbon dioxide and water. You then breathe out the carbon dioxide and either sweat or urinate out the water.
Does this mean that just breathing can help you lose weight. The answer is that breathing helps you lose a little weight. Estimates are that deep breathing can help increase weight loss by 2%.
Irisin Actually Increases the Number of Fat-Burning Brown Fat Cells
You have two types of fat cells. White fat cells store fat. Brown fat cells burn fat. Brown fat cells are the fat cells which are activated when you get extremely cold, for example. They activate to make you shiver and shivering keeps you warm.
People who are naturally skinny have more brown fat cells than people who struggle to lose weight.
It turns out the irisin, in addition to unlocking the door to release fat from your white fat cells, also helps to trigger the creation of more brown cells. Studies in 2009 from Harvard Medical School on mice discovered this special ability of irisin. Irisin appears to convert white fat cells into brown fat cells.
How to Increase the Amount of Irisin
Exercising intensely is the most proven way to boost levels of irisin.
The only other proven way to boost irisin is to subject yourself to temperatures cold enough to make you shiver.
Shivering is not something that you should try to induce, especially if you are older. Infants d young children have more brown fat than adults and teenagers. This is why children and infants do not get as cold as we do and do not shiver.
Our body's ability to make us shiver as the temperature drops also ages itself. The old thermostat becomes insensitive to changes. This is why it is easier for you to freeze to death as you get older.
The best and safest way, therefore, for you to increase irisin levels is to just exercise more.
Start slowly if you haven't exercised in a while. One great way to add intensity to your fitness is just to walk faster.
Also, take the stairs. Add one or two flights a month.
If you are over 50, think hard about adding a program of strength training to your week, 3 times per week.
If you can't afford a trainer, use your own body weight to start. Try doing sit-ups, try doing a half or full push up. And by all means, try doing squats. Anything you do which makes you lift or hold up your own body weight is a form of weight training.