9 Trainers Share the Top Weight-Loss Mistakes People Make in the Gym  

“I often refer to this situation as the ‘moving couch potato,' or the person on the elliptical for an hour who isn't doing much. It’s important to be aware of your level of effort by monitoring your heart rate. For low-intensity exercises, like hatha yoga or hiking, aim for 50 percent of your max heart rate. Moderate-intensity exercises should get you to about 65 to 75 percent, and vigorous intensity is 80 to 85 percent.” —Cat Fitzgerald, C.S.C.S., of NY Custom PT & Performance

RELATED: 5 Treadmill Hacks That Can Help Shave More Pounds 

“Doing the same thing and expecting a different result is the definition of insanity. You've got to change up your workout to lose that last bit of weight. For example, if you’ve been running long distances, try adding short-distance sprints. If you’ve been following a weight-lifting routine, add some sort of cardio. By switching up your exercises, you keep your body guessing and get faster results.” —Matt Tanneberg, C.S.C.S., of Arcadia Health and Wellness Chiropractic (Spice up your sweat session with these moves from Women's Health's Look Better Naked DVD.)

“When it comes to training and losing weight, bigger movements are the better option. For instance, compound multi-joint movements, such as a pushups, deadlifts, pullups, or squats, involve more muscle groups and require more energy (you know, calories) than single-joint exercises, like a bicep curl. Building muscle with compound movements also raises your metabolism, so you burn more calories at rest.” —Wes Showalter, C.S.C.S., interval and cycling coach at Studio Three

RELATED: 5 Ways to Boost Your Metabolism in the Morning

“I witness hard-working clients, who just made significant efforts to get them closer to their goals, order a burger and fries or an ice cream post-sweat. Giving your body the gift of movement doesn't call for a celebratory meal.”  —Rocky Snyder, C.S.C.S., of Rocky’s Fitness Center

“The only people who need protein shakes are bodybuilders, high-level athletes, and vegetarians who require an alternate form of protein supplementation. If you're at the gym slugging a protein shake, odds are it's just extra calories and loaded with sugar—two things you don't need if you want to lose weight.” —Kevin Steinmuller, C.S.C.S.,

"If your goal is fat loss, your rest periods need to be short and sweet. Try this strategy: Set a timer on your watch or phone for 10 minutes. Then bounce back and forth between two relatively simple exercises, like bench press and deadlift. Do as many sets as possible before your timer goes off. Racing the clock helps you stay focused." —Rob Sulaver, C.S.C.S., of bandanatraining.com

“Skipping strength training will sabotage weight loss. As you lose weight, you also lose muscle mass, which wrecks your metabolism. Dedicate 40 to 65 percent of your gym time to strength training (that's 24 to 39 minutes of an hour-long workout)."—Rachel Straub, C.S.C.S., co-author of Weight Training Without Injury: Over 350 Step-by-Step Pictures Including What Not To Do!

“Overtraining can really hurt your weight-loss goals. The results people want to see from exercising are achieved during recovery and proper nutrition. When recovery is compromised, it can be very difficult for the body to change. I constantly remind my clients that more does not always equal better. Fitness is more fun when you don’t brutalize yourself in the name of results.” —Ross Anti, C.S.C.S., personal trainer on GoodLooks

“High-intensity interval training (HIIT) increases your heart rate and enables fat burning, which will continue after you're done working out. Combining aerobic and anaerobic exercise into your cardio regime will prevent boredom and rev up metabolism.” —Lauren Simmons, R.D., C.S.C.S., of Core Dynamics