Oh you know how much I despise myths and misconceptions when it comes to health, nutrition and fitness! Well one load of crap that continues to irk me, and to still be spewed by many health professionals is that lifting heavy weights will make you big and bulky so if you are looking to be lean, you should use only light weights and body weight exercises. THIS IS A LOAD OF BULL SHIT!
"But come on," you say, "Look at Gwyneth Paltrow, she does the Tracy Anderson Method!" And yes, this is the B.S. spewed by Anderson, and many other health and fitness 'experts' too.
Sorry. It isn't true.
Not only is it not backed by science, it actually violates the underlying principles of fitness. Ever heard of progression?? Well, basically, the body adapts to the demands you place on it relatively quickly. So you will stop making gains and get diminishing returns on your fitness routine unless you increase the difficulty. So all these folks who recommend you should just do body weight exercises or use super light dumbbells are...dumbbells! Take body weight exercises, for example. Sure, they may initially allow you to improve your cardio and strength if you are starting out relatively unconditioned. But if you lose weight, than these exercises become easier. In addition, when you lose weight your metabolism declines because it takes less energy to move your body. Also, unless you are actively building muscle, a decrease in calorie intake leads to a loss of muscle along with fat mass. The proportion of lean mass (muscle) you have, is what determines your metabolic rate. Get it?
As Dr. Willey points out in his book, research has demonstrated that training should be progressive to get the best results. That means increasing your weight/resistance load!
Unfortunately, misunderstandings about training principles abound. In my Essentrics program, I hear this B.S. all the time. Creator, Miranda Esmond-White, goes on about how the program can help with weight loss. Now, while it is fabulous for preventing pain and maintaining mobility because of the P.N.F. and dynamic stretching, this is no weight loss exercise! Sure, some of my very unconditioned, obese clients say it gets them huffing and puffing, but for me, it doesn't even get my heart rate up a single beat. It is not the 'no-impact cardio' she claims it is. It also is not going to create long, lean muscles, rather than the 'bulky' ones you get from using weights, like she claims. Sorry! Again, the body weight exercises will certainly help improve your strength if you've been previously sedentary and certainly the plies and leg lifts get challenging after a while, but, again, this whole light weights = lean while heavy weights = bulk is crap.
In his book Beat the Gym, Tom Holland points out that the reason yoga and Pilates class devotees tend to be lean is not that these classes are great for burning fat, its because they are self-selecting. Absolutely true! Gwyneth Paltrow has always been lean. Miranda Esmond-White is a former professional ballet dancer. Lean folks gravitate towards these activities because they don't need to lose fat. They are likely genetically inclined to be lean and have never had excess weight to begin with. Remember, its harder for those who have excess fat cells to lose weight and keep it off than it is for those who have never had excess fat cells to keep lean.
A recent study discussed in the New York Times demonstrated that there are significant differences in the way different people respond to exercise, whether its cardio or weight training. Ultimately, the best combination for keeping you lean may be different than the person beside you. But if you need to lose fat, than it is likely that the easiest way to do that will be with progressive strength training along with cardio.
That being said, other studies, like those by Dr. Stuart Phillips, have found that the actual amount of weight you lift, heavy or light, doesn't matter, the key is lifting to failure. But the thing is, if you lift lighter weights, this will take longer, like 20-25 reps rather than 8-15. In addition, if you adhere to the principle of progression you will have to either eventually increase your weight, or keep upping your reps and/or sets, which again makes your workout take longer. Thus, its more efficient to lift heavier weights.
Over the last few years I have increasingly focused on strength training, including heavy weights, and have not turned into the Incredible Hulk. In fact, my clothing size has stayed the same and I am as lean as I have ever been...despite the fact that I eat like a wild animal.
"But I don't want to look muscular", you say? The extent to which you will develop muscle definition depends on genetics, what type of training you do (# of reps, sets, rest, etc.) as well as the amount of body fat you have. So yes, according to everyone who sees me, you can tell I lift weights. Here's the thing though, if you are not naturally long and lean, and most of us aren't, than you will have to do a heck of a lot more than body weight leg lifts to get that way. You will have to eat a very low calorie diet and possibly even do a lot of high intensity cardio. This is neither healthy nor an enjoyable way to live (unless you like being hungry all the time). If you can accept having a strong, muscular body, you can maintain that eating heartily and healthfully, which, seems preferable, if you ask me.
Remember, we lose a significant percentage of muscle mass each year after age 30. This is why many people gain weight as they age. Actually, your absolute weight may not change noticeably but your proportion of lean mass is decreasing while your proportion of fatty tissue is increasing, putting you at increased risk of chronic illness, loss of mobility and injury. So yes, moving your body is key, but also lift some weights too!