Weight training is a slippery slope for a lot of women. Many are afraid of bulking up and skip it altogether, while others — including actress Kristen Bell — use lighter weights to avoid looking too muscular. The accepted logic is that heavier weights equal big muscles and using lighter weights is the best way to slim down and maintain "womanly" tone. Not so, says a recent article in the New York Times: using heavier weights is more slimming than you think.
First things first. The article challenges the notion that lifting big weights means you're going to get big muscles. There is a reason that bodybuilders are so fond of those mega-calorie extreme protein shakes; if you want to go big, you have to eat big. Those bulked up folks you see now and again are probably eating an excess of 2,000 calories a day.
To find out what weights you should be lifting to lose body fat,
If you want to be stronger and toned but still look slim, the suggestion is to challenge yourself with heavier weights and fewer repetitions. A 2002 study that looked at women doing both low- and high-intensity resistance exercises found that those who lifted heavier weights with fewer repetitions burned more calories and had a bigger metabolic boost than the women who lifted lighter weights with increased repetitions. When deciding how much weight you should be lifting, the women with the greatest success in the study did two sets of eight repetitions at 85-percent of their maximum ability. Using this measure, you should pick a weight that you can lift eight times without straining, and whichever muscle you are working should feel tired (but not exhausted) upon your final rep of the first set.
Additional evidence supports this claim: in a study published last year, scientists followed 122 women for six years and found that those who did less repetitions with heavier weights lost the most body fat. If you need physical evidence, look at Cameron Diaz. Cameron uses 20-pound weights in her everyday workouts — I challenge anyone to compare her svelte frame to that of the Incredible Hulk!