Here’s good news and bad news for plus-size exercisers who can’t lose weight: The bad news is that all this time you’ve been exercising wrong.

The good news is that your failure to lose weight is—and you can bet on this—the result of doing things wrong instead of “fat genes.”

Really, you should be thrilled to hear this, because if you’re doing something wrong, you can correct that practically overnight.

Whereas if being overweight is the result of genetics…it will be very tough to lose all the weight you want to lose.

Though I see this first sabotaging problem with people of all sizes, it’s particularly prevalent among obese and moderately overweight people: holding onto the treadmill.

Eliminate this mistake at once. Not only does this discourage working harder (because the “harder” you try to work, the tighter your grip on the machine becomes!), but it burns 20 percent fewer calories than if you moved hands-free at the same speed and incline.

LET GO. Note that the majority of treadmill users who are not holding on have fitter, leaner bodies.

—– WEIGHTS —–

A most striking mistake that I see among obese women (not so much with men) is using very light resistance for their weight workouts.

This is a universal phenomenon I’ve seen throughout the years, at every gym I’ve ever been to, and it is a major saboteur.

It’s not that plus-size women can’t lift heavier. They sure as heck can. I used to be a personal trainer and had my big female clients lift as heavy as they could.

The problem is that they think that lifting heavy will make them even bigger.

Lifting heavy will NOT increase the size of fat cells! The only thing that inflates fat cells is eating more food than your body can burn off. That’s the equation: calories in vs. calories out.

Though there are variables that slow resting metabolic rate, it still comes down to calories in vs. calories out at the end of the day.

One way you can speed up resting metabolic rate is to add lean muscle to your body. As you add lean muscle and this new muscle feeds off your stored body fat, you will lose fat and get SMALLER.

Don’t believe for a moment that your tree trunk legs will get even heftier if you’re leg pressing large amounts of weight.

If you stay at lighter weights…you won’t be challenging your body enough to add lean muscle. Instead, you’ll just build up endurance.

So if you’re doing only 45 pounds on the lat pull-down machine, this just won’t cut it. Go up to 75, even 90 pounds, and put some elbow grease into it. Shock your body.

THIS is muscle confusion: lifting heavier weight than what your muscles are used to. This will spur fat-burning.

Another saboteur of weight loss in obese people (and this includes some men) is the type of strength training move.

I rarely see obese women and men doing the very exercises that burn the most fat: the deadlift, some variation of the squat, the bench press, overhead barbell press and heavy kettlebell swing.

I do see many overweight women doing lat pull-downs and cable rows—but of course, with insultingly low weight.

Obese people tend to do too many isolation exercises such as dumbbell kickbacks, dumbbell and cable curls, machine crunches and dumbbell side lifts.

Yes, there are buff and cut bodybuilders who do these, but they also spend more time doing the big compound movements like the deadlift, bench press, incline bench press, dumbbell press, leg press and squat.

Get off the floor and into the free weight area. Forget the reams of sit-ups, crunches, side bends and leg raises.

Ditching all of these saboteurs will mean you’ll finally start seeing the weight loss you’ve been wanting for so long.

Lorra Garrick is a former personal trainer certified through the American Council on Exercise. At Bally Total Fitness she trained women and men of all ages for fat loss, muscle building, fitness and improved health.