You can step on a scale or try squeezing back into your old jeans to determine whether you’ve gained weight. But what if you were able to forecast whether you’ll be fat? It’s all in your breath. According to a study published in the Journal of Clinical Endocrinology & Metabolism, a simple breath test can tell whether you’ll have a tendency to become overweight.

The secret is an overgrowth of a certain bacterium in the gut. When this bad microbiome takes over the good ones, you may feel bloated, constipated and get diarrhea. This situation predicts a predisposition to obesity.

For the study, researchers had participants drink a sugary beverage and took breath samples every two hours. They also measured body mass index. Some participants exhaled higher levels of methane and hydrogen, indicating an overgrowth of this bad bacteria.

More research is needed, but adjusting levels of bacteria could be the next weight loss treatment on the horizon. Probiotics, which help rebalance bacteria in the gut, could also be a viable treatment. But in the meantime, bearing too much bad bacteria in your gut doesn’t have to spell certain obesity for anyone. Maintaining an active lifestyle and watching what you eat — and what you weigh — are key to keeping trim. Weight gain doesn’t happen overnight, so be sure to step on the scale every once in a while.

But if you find yourself in the danger zone and want to drop pounds, just be sure to do it safely. Focus on eating fruits, vegetables, lean protein, soy products and nonfat dairy foods. Avoid grazing when you’re bored and don’t eat while watching TV. Drink tons of water and stay busy. Get up and move around every so often. Don’t skip meals and write down everything you eat. And take a deep breath.