When to Drink Water to Boost Your Metabolism, According to Dietitians

Technically speaking, the best time to drink water is all day, throughout the day, every day. Consistent intake is the best way to ensure that you don’t fall behind on your water intake, which may cause fatigue. That said, Anar Allidina, M.P.H., R.D., a registered dietitian based in Toronto, does have a preference for when to drink water if your goal is to boost metabolism.

“The best time to drink water is when you wake up, since you are in a state of dehydration while sleeping,” she says. “Aim for 12 to 20 ounces within 30 to 60 minutes of waking to help rehydrate cells and to support gut health.” If that water is cold, it may also prompt water-induced thermogenesis, in which your metabolism spikes briefly to warm the water to body temperature. “By drinking cold water, we actually burn calories,” says Vicki Koenig, R.D., C.D.N., a masters-level registered dietitian based in New Paltz, NY. From there, and especially if you eat breakfast within two hours, your metabolism will be off to the races for the rest of the day.

In addition to the morning, the experts we spoke to stressed the importance of drinking water before exercise. “The best time to stay hydrated is when you’re expecting to use or lose more water,” says Koenig. “With increased exercise, we need more water.” It’s also smart to taper your water intake after dinner as you approach bedtime, both Allidina and Koenig say. “Heavy fluid intake late in the evening may disrupt sleep due to nighttime urination, which can indirectly impair metabolic health by reducing sleep quality,” Koenig explains.

Water plays an important role in metabolism at the cellular level. “Hydration supports energy production in our cells,” says Allidina. “Every metabolic reaction in your body requires water. Even mild dehydration can slow cellular energy production, fat oxidation, and nutrient transport.” The American Sports & Fitness Association explains that the body requires water to break down adenosine triphosphate (ATP), which is the main energy currency for cells. Without water, ATP is unable to release energy for cells to use—the energy is essentially behind a locked door, and water is the key.

Beyond its crucial part in releasing cellular energy, the benefits of water for metabolism only multiply. “Hydration supports metabolism by maintaining normal cardiovascular function, thermoregulation, digestion, nutrient transport, waste elimination, and physical performance—all of which influence energy expenditure and metabolic efficiency,” Koenig says.

“Optimal hydration is where intake matches need,” says Koenig. “It’s helpful to pace oneself and plan for the day.” If front-loading your water earlier in the day helps you drink enough to stay energized and avoid dehydration, that’s an excellent strategy. But if you prefer to spread your drinking more evenly throughout the day and you aren’t getting up in the middle of the night to use the bathroom, that works too. The key, reiterates Koenig, is to provide the body with what it needs to keep your energy levels steady and your metabolism humming.