Experts warn against overestimating water loss during exercise in heat

Health experts highlight the risks of exercising in extreme heat, emphasising that weight loss from sweat is temporary, and encourage proper hydration and balanced activity for long-term fitness.

Exercise in extreme heat and humidity can do more than leave people tired and sweaty: it can raise the risk of dehydration, heat exhaustion and, in severe cases, heatstroke, according to Johns Hopkins Medicine and the Cleveland Clinic. In that context, Doha nutrition specialist Aisha Saqr has warned against treating a heavy sweat as proof of an effective workout, arguing that a drop on the scales after exercise usually reflects water loss rather than fat reduction.

Saqr, who works as a therapeutic nutrition and obesity specialist at the Turkish Hospital and teaches at the Community College, said the body’s weight is made up largely of fat, muscle and water. She said that when exercise causes fluid loss, the number on the scales can fall quickly, but that change is temporary if the lost water is replaced. Real weight loss, she said, depends on a sustained pattern of balanced eating, regular movement and a healthier calorie balance over time.

Medical guidance from Johns Hopkins, the Mayo Clinic Health System, MedlinePlus and UCLA Health broadly supports that view. Those organisations advise people to reduce workout intensity in hot weather, drink before, during and after exercise, take breaks and choose cooler times of day when possible. They also caution that heat and humidity make it harder for the body to cool itself, increasing the risk of dizziness, nausea, fatigue and other symptoms of heat-related illness.

Saqr also said people with chronic conditions such as diabetes or high blood pressure should check whether their chosen activity suits their health status and seek medical advice if needed. She recommended light meals before exercise, avoiding heavy or fatty food, and listening to the body if unusual dizziness or nausea appears. Her message was that exercise should be a regular part of daily life, not a short-term tactic for fast weight loss, and that lasting results depend on combining movement, sensible nutrition and adequate hydration, especially during the hottest months.