Losing 10 pounds safely takes between five and ten weeks. Mayo Clinic explains that it's best to aim to lose one or two pounds per week, as faster weight loss is unhealthy, unsustainable and likely to reverse itself.
Mayo Clinic explains that a daily deficit of 500 calories leads to losing one pound per week, while a 1,000 calorie deficit leads to losing two pounds. This caloric deficit should come from a combination of both diet and exercise because over-exercising and under-eating impede weight loss.
The CDC notes that losing even 10 pounds can improve blood pressure and daily functioning while decreasing the risk of obesity-related diseases, such as Type 2 diabetes and coronary heart disease.