How Long After Eating to Wait for An Empty Stomach

For many of the Biotest supplements, the label suggests consuming on an empty stomach. I was wondering if there was a rule of thumb for how long to wait after a meal to achieve an “empty stomach”.

The specific example I had in mind was taking ZMA before bedtime. The label recommends taking on an empty stomach and to avoid calcium supplementation at the same time. In addition to the ZMA, I always have a Metabolic Drive shake as my last meal of the day before bed and I try to take the shake an hour before the ZMA to avoid the high levels of Calcium in the Metabolic Drive interfering with the ZMA.


There’s no real rule of thumb since gastric emptying varies greatly depending on the meal eaten. The only real time the stomach is empty is upon waking.

So that generally means to take before eating, give it a little time, then eat. Also, some supplements may suggest an empty stomach to avoid any issues with competing nutrients, while others recommend it so you’ll “feel it” faster (like fat burners with stimulants.) There are also some in the nutritional science community who say that it’s perfectly okay to take things like ZMA with calcium. It’s a debated issue.

But an easy solution for ZMA is to take it before the last feeding of the day, like maybe 30 minutes or so. I often recommend that with Z-12 as well so it’ll get into your system faster and go to work without having to fight it out with your pot roast and sweet potato.

Lastly, and very generally speaking, if one were to take most supplements with food even though they recommend an empty stomach, that doesn’t mean the supplement is totally cancelled out. Most of the time, it’ll still do its thing, though maybe not at 100%. Again, it depends on the type of supplement.

In short, it’s usually nothing to worry about.

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Disclaimer: Individual results may vary.