Water for weight loss

Congratulations to Danielle Perry and Dr Karenn Chan for their practical article in the July 2022 issue of Canadian Family Physician that presented current evidence¹ of an association between increased water intake and change in body weight and composition in individuals who were overweight or obese.² The article includes valuable and practical information for primary care physicians, but I would like to add a current randomized controlled trial to the evidence on the topic of water for weight loss.

Sedaghat and colleagues evaluated the effects of water intake before meals in 40 patients with type 2 diabetes mellitus who were overweight.³ The intervention group drank 250 to 500 mL of water 30 minutes before each main meal for 8 weeks. Compared with the non–pre-meal water group, there were statistically significant reductions in energy intake (−174 kcal), fat intake (−21 g), body weight (−1.35 kg), body mass index (−1.28 kg/m²), waist circumference (−3.0 cm), and serum levels of fasting blood glucose (−32.6 mg/dL or −1.81 mmol/L), low-density lipoprotein cholesterol (−13.37 mg/dL or −0.35 mmol/L), and copeptin (−2.7 pmol/L). And it is also documented in both children and adults that elevated copeptin levels (the C-terminal component of arginine vasopressin) are statistically significantly associated with high body mass index and waist circumference.^4,5

More water equals less hunger: in my practical work as a nutrition scientist, over the past 25 years my patients who were overweight and obese have confirmed this intervention step, which is easy to implement, with the following words: “Drinking more water before every meal accelerates the feeling of satiety,” “You will not have any more sudden, ravenous cravings because of the 2 glasses of water you drank before eating,” “The best tip for long-term weight management is to drink more water before eating,” or “If there is already a lot of water in the stomach, less food fits in.”