Celebrity trainer Gunnar Peterson explains the reason(s) behind your belly bloat—and what to do about it.

There hasn’t been a Monday I haven’t been asked this question. So a few things to consider when your weight fluctuates:

1. Did you eat ethnic foods? Many—Japanese, Chinese, Mexican—are high in sodium/sugar, which can cause fluid retention. If that’s what you feasted on, drink more water (it actually helps the body remove water) and your weight will drop.

 2. Did you booze it up? Alcohol acts as a diuretic, which can cause dehydration, says my nutrition guru, Philip Goglia, Ph.D. That, then, makes your body hold on to water. Cut back and you’ll be fine.

3. Did you drink sparkling (mineral) water? It’s high in sodium. Go back to flat water to drop the pounds.

4. Did you do a lot of cardio? Several high-cardio days can cause water retention. Keep cardio to a max of an hour a day at a static heart rate and you’ll bounce back shortly.

Gunnar Peterson is a celebrity personal trainer and columnist for Men’s Fitness. Follow him on Twitter