How Important Is Strength Training?

"Loss of muscle is actually one of the reasons yo-yo dieters can't seem to lose weight. They lose and gain over and over again. This in itself is annoying, but the big problem is that when they lose weight, they lose half muscle and half fat (the body holds on to fat preferentially as a natural survival mechanism), and when they gain the weight back, they gain back all fat for various reasons. Since muscle is much more metabolically active and burns seventy times as many calories as fat cells, losing muscle slows down their metabolism, making it easier to gain weight and harder to lose it, even while they eat the same number of calories.

Unfortunately, it's easier to gain and retain fat than it is muscle, and while losing fat takes work, losing muscle is (literally) effortless. Loss of muscle happens after the age of about 35 if you do nothing to prevent it (smaller losses can occur even earlier if a person is sedentary.) This loss of muscle has a tremendous impact on your ability to lost weight. This is why older people have such a tough time losing weight."

More muscle = more mitochondria, which is central to boosting your metabolic power.

1. Eliminate the causes of mitochondrial damage.
(Eat a nutrient-dense, phytonutrient-rich, unrefined, unprocessed, real, whole-food diet.)
2. Exercise intelligently.
(Do interval training and aerobic training.)
3. Eat foods that turn up your metabolism, and avoid foods that turn it down.

(Above From Ultrametabolism)

I know so many women who think they bulk up from strength training. You don't have to pump serious iron to keep your muscle. Just be active and try and incorporate activities in your life that will increase your strength i.e. hiking, rowing, biking up hills, walking up hills, skiing, etc. But remember that PAST THE AGE 35 YOUR BODY NATURALLY STARTS LOSING MUSCLE UNLESS YOU DO SOMETHING TO PREVENT IT. That's part of the reason why women have a hard time losing weight the older they get.