Bob Harper hasn't just helped hundreds of people lose weight as a trainer and host on The Biggest Loser; the 53-year-old lost 40 pounds himself [1] after suffering a near-fatal heart attack [2] in 2017. So when Bob offers up weight-loss advice, we listen.

In an Instagram video as part of a series he calls #TwoCupsIn, Bob revealed what he believes to be the biggest saboteur for weight loss [3]. "If you are trying to lose weight, nighttime snacking is going to be the worst thing that you can do," he said in the video. "Everybody has been asking me about nighttime snacking, and I'm just going to have to tell you, this is where self-discipline has to come into your life."

Instead of opening up your pantry or fridge for the millionth time at night, Bob suggests distracting yourself out of the kitchen [4]: drink water, read, meditate, or go to bed early. And while some people may think a small snack is harmless, he wants people to learn the self-control of not mindlessly munching [5] out of boredom after dinner.

"Really focus on those goals and go, 'I know I'm going to get up tomorrow and I'm going to feel so much better,'" he said. "Try it; I know you've got it in you."