Indeed, the Mayo Clinic says that the concern with fast weight loss is that it usually takes extraordinary efforts in diet and exercise — “efforts that could be unhealthy and that you probably can’t maintain as permanent lifestyle changes”.
It adds: “Hundreds of fad diets, weight-loss programs and outright scams promise quick and easy weight loss.
“However, the foundation of successful weight loss remains a healthy, calorie-controlled diet combined with increased physical activity.”
A high amount of body fat can lead to weight-related diseases and other health issues. Being underweight is also a health risk, notes the CDC.