Strength training is crucial to preventing the post-30 loss of muscle mass, which can slow down metabolism by as much as five percent each decade. But using those padded strength machines at the gym is like watching TV with the sound off — you don’t get the full effect. "Weight machines are a good place to start," says Roberts, "but sooner or later you need to graduate to dumbbells." Dumbbell exercises involve a greater number of muscles because your body — and not the machine — provides stability. And the more muscles you work, the more calories you burn. Free weights are also more versatile: You can do traditional moves like a shoulder press with only one arm, or bicep curls standing on a balance disc. Just make sure the weights are heavy enough to challenge your muscles (meaning that you can lift them for only eight to 12 repetitions before you get exhausted). Aim to work with weights two to three times a week; a vigorous yoga class can also substitute for a weight session.
If you spent your 30s: Eating three square meals
From now on: Graze all day
Eating five or six smaller meals instead of three larger ones can help prevent both hunger and overeating. Mini meals steady blood sugar levels and slow down the release of insulin, a hormone that can cause your body to store more fat, explains Maye Musk, RD, a New York-based nutritionist. The emphasis is on mini: If you aim for 1,800 calories a day, you’ll average about 300 calories at each of six meals. A mix of protein and high-fiber carbs helps you stay fuller longer. Musk’s favorite combos include a hard-boiled egg with a piece of whole grain toast; nuts and dried cranberries; and a stick of string cheese plus an apple. Have the first mini-meal early in the day: Numerous studies confirm that eating a morning meal keeps blood sugar levels stable and can help ward off hunger during the afternoon and evening.
Changes to Make, Continued
If you spent your 30s: Walking or jogging three miles
From now on: Add intervals
Sure, a 40-minute steady slog on the treadmill is ideal for catching up on the nightly news or the latest episode of Lost, but your session can be a lot more productive if you add intervals. This is how it works: Increase the intensity of your aerobic routine to near your limit for anywhere from 20 seconds to two minutes, then spend about an equal amount of time exercising at a level that feels comfortable. Continue alternating the sequence during your workout. This kind of training turns your body into a more effective fat-burning machine because the harder you work during the session, the higher the energy expenditure and the longer your metabolism stays elevated. Switching intensities also teaches your body to become more adept at delivering oxygen to the muscles and taking away waste products, so you can exercise longer without getting tired. Plus, you continue to burn more calories after the session is over because your body has to work harder to recover. Some recent studies pinpoint the benefits. Australian researchers reported that women who interval-trained on stationary cycles three days a week (doing eight-second speed bursts followed by 12 seconds of recovery for a total of 20 minutes) lost nearly five pounds more than those who did a slow, steady 40-minute routine — and lost more than 10 percent of their belly fat in the process. In another small study, subjects who ran in 20 one-minute speed bursts followed by two-minute recovery periods burned twice as many calories post-workout as they did with a single 30-minute, steady paced session. Because the training puts some stress on your body, limit your interval sessions to no more than two or three times a week, Coopersmith advises. It’s fine to strength-train or do some cardio at a steady pace on the other days.
If you spent your 30s: Being a carb junkie
From now on: Pump up your protein intake