Today we’re going to explore whether drinking water can lead to a decrease in total calorie (energy) intake. Weight loss is ultimately achieved via a calorie deficit, but it’s not only a matter of calories in vs calories out, as our metabolism is more complex than that and some foods are absorbed differently by the body.
There are a few studies examining the effect of water directly on weight loss, and whether it results in a decrease in total calorie intake. We dive a bit deeper to see if replacing foods with water is an effective way to reduce calorie intake or if it’s a bit of a myth.
Can water intake reduce hunger?
Drinking a lot of water is generally believed to support weight-loss efforts or maintenance and has become a commonly used practice for weight control.1 Drinking plenty of water every day is good for overall health. Plain drinking water also contains no calories, so it can help with managing body weight and reducing calorie intake when substituted for drinks with lots of calories, like fizzy drinks.2,3
Thirst, the sensation we feel when mildly dehydrated, is often mistaken for hunger by the brain. Drinking plenty of water while trying to lose weight is good because you consume water instead of other beverages, which are often high in calories and sugar.4
The effects of having water with meals rather than drinking nothing or various other drinks remains under-studied. Without water humans can survive for 2–4 days. Water makes up to about 60% of our body weight and is critical for life5. Reduced energy (calorie) intakes can be expected if you replace higher-calorie beverages with water when you’re eating but this may not translate into long-term weight changes.6
Short-term effects of water consumption include increased fullness, reduced feelings of hunger7, and slightly increased energy expenditure as the result of a proposed water-induced thermogenic effect (increased heat production in the body).8
Is this strategy always reliable?
Drinking water for the purpose of weight loss alone or as a replacement for nutrient-rich food is certainly not recommended. We need food for nourishment and energy. Water cannot provide these and should be drunk for hydration. It’s important to not get into an all-or-nothing way of thinking with water. Yes, it has many benefits (aiming for 6-8 glasses of water per day is good) but we should not replace food with water.
Ultimately, this causes low energy and mood, and only increases the risk of nutrient deficiencies.
Water is a great replacement for high-sugar beverages, but it’s important to remember that drinking water needs to be combined with a calorie deficit to lose weight.
Take home message
While we certainly don’t disagree that drinking more water is beneficial, it should always be included as part of a well-balanced diet and should never a replace a nutrient-dense diet. Food and good hydration come first. Replacing sugar-sweetened beverages with water can have many benefits for weight management, but replacing water for meals is a big no-no.