With the start of the New Year, there's s surge in gym memberships and cable TV infomercials on how to lose weight. For many, getting in shape is synonymous with losing weight, though the two are not the same things.
You can lose weight by eating fewer calories and still be out of shape. Likewise, you can be in pretty good shape, i.e., normal blood pressure, OK lipids, and also overweight. Some 300 pound NFL lineman are in tremendous physical condition, while many skinny people are not.
However, most of us do equate fitness with leanness, which is usually measured in percentage of body fat. Exercise physiologist Covert Bailey was one of the first to get that concept in front of the general public in his Fit or Fat books over twenty years ago. Healthy range of body fat is different from males to females. In general, a healthy male may measure between 10-20% body fat, and women 15 to 25%. This number goes up slightly with age. The number also varies even in elite athletes, depending on their sport. Marathoners can be in the 5-7 range, while swimmers are twice that.
So what's the advantage of a low percentage and what does it have to do with fitness and health? Leanness means less wear and tear on your skeleton, especially your joints. Your heart does not have to work so hard for the same amount of physical work, thus improving your endurance. Most importantly, leanness, when combined with exercise, reduces the amount of body inflammation suspected to cause many chronic diseases.
I've recently been reading two excellent books on body fat and exercise: 1) Robb Wolf's The Paleo Diet, and 2) Tim Ferris' The 4-Hour Body. Both are based on a similar premise: you will lose weight if you restrict simple carbohydrates in your diet. Wolf says to eat mainly high quality protein, vegetables, and fruit, but no wheat or legumes. Ferris says okay to legumes (because if you don't eat them you won't feel full and be hungry all the time), but no to fruit (fructose is a sugar, the digested final product of all carbs). Both these books are based on good science; the references are there if you want to find out for yourself.
I think these authors are in their late 30's, about the time most humans have just passed their athletic prime and when percentage of body fat tends to start to drift up, especially around the gut. As a result, they are a little body image-obsessed. Ferris even goes so far as to have pictures of his shirtless torso as proof his diet works. (I'm much more impressed when he does 180+ kettlebell snatches on YouTube.) Ferris gets excited when his body fat percentage gets so low he can see the veins popping out underneath his skin. Pretty funny.
This TOJ thinks both of them offer sound advice on eating and exercise, and there's no doubt that for most people, lowering percentage of body fat by reducing simple carb intake (especially anything with white flour or sugar) is good for you. In the past few years, the evidence has mounted that consumption of simple carbs elevates insulin and causes insulin resistance, which is linked to Type-II diabetes, cardiovascular disease, and some cancers.
Percentage of body fat is a much more reliable indicator of health than the popular Body Mass Index (BMI). Many very fit athletes have high BMI's because muscle is much heavier that fat. Muscle is preferable to body fat because muscle raises your metabolic rate and lowers insulin levels, especially when the muscles have been exercised. Fat can't do that, it's just along for the ride.
If you follow the diet and exercise advice of either Wolf or Ferris, expect to lose fat, not necessarily weight. A pound of fat takes up four times as much space as a pound of muscle. When you combine a high protein diet with exercise, especially with lots of resistance exercise, you will lose body fat and increase muscle. The surest sign you are will be in looser clothing, especially around your waist, thighs, and butt.
Who knows if you'll see changes in the mirror, but you'll feel them. That's what really counts.