Often, you’ll hear people claim that there’s a “better” time of day to take collagen—and in doing so, you’ll increase its efficacy. Here’s what the experts have to say about the most common claims, plus a tip on when to actually take yours: Your stomach produces even more acid when the vagus nerve, which helps regulate digestion (among other things), is stimulated, he says. “The presence of food in the stomach further stimulates acid secretion,” Galligan says. Acid is required to break food down, but collagen survives passage through your stomach, he explains. Ultimately, it doesn’t make a huge difference if you take collagen on a full or empty stomach. “The bulk of the breaking down of proteins actually happens in the small intestine, so full stomach, half-full stomach, or empty stomach—there will be little difference,” says Scott Keatley, R.D. “On their own, collagen supplements are unlikely to fill you up because of the small volume of each,” he says. However, having something with fiber and fat in it, like a smoothie with nut butter, along with your collagen supplement “will help satisfy your appetite better than a sugar- or carb-based snack,” says Albert Matheny, M.S., R.D., CSCS. But if you just take it with a midday coffee, it will fill you up just about as much as a coffee would otherwise. Matheny agrees: “Think of collagen as more of a general in-your-system-type supplement,” he advises. Not only that, but it takes anywhere from three to five hours for collagen to get from your mouth through your small intestine, where it’s absorbed, so this could be a tricky thing to try to sync up with your REM cycle, Keatley says. Ultimately, you should take your collagen supplements whenever it’s easy and convenient for you. The key is to find the time of day that you can make it part of your routine—because any supplement works best when you actually take it.