The first step in answering this question is to consider the numbers. In order to lose 50 pounds in 2 months one would need to lose just under 1 pound per day. This type of drastic rapid weight loss would require a calorie deficit of 175,000 for the total 50 pounds or approximately 2,920 calories daily. For a woman weighing 200 pounds it would require over 5 ½ hours a day of walking at a 4 mph pace to burn approximately 2,920 calories. Not only would it be necessary to exercise to this extreme amount but it would need to be done while only eating the calories necessary to sustain life.
The calories necessary to maintain life is called the Basal Metabolic Rate or BMR. The BMR is calculated for women as [(Weight in pounds * 4.35) + 655] + (Height in inches * 4.7) – (Age in years * 4.7) = BMR. The BMR is calculated for men as [(Weight in pounds * 6.23) + 66] + (Height in inches * 12.7) – (Age in years * 6.8) = BMR. For this example of a 200 pound woman who is 5’7” in height and 40 years old her BMR would be calculated as [(200 * 4.35) + 655] + (67 * 4.7) – (40 * 4.7) = 1,652 calories. This means that she could eat 1,652 calories daily while burning 2,920 calories daily or she could reduce her calories to 1,200 calories daily while burning 2,468 calories daily. While the amount of calories available for daily consumption appears to be realistic, the daily amount of exercise does not appear to be realistic. Unless you are willing to have your entire life be centered on exercise and weight loss with little to no distractions such as work or a social life then over 5 hours of daily exercise is not feasible for most people.
Another concern which comes with exercising for excessive amounts of time while consuming a restricted calorie diet is the risk of low blood sugar. Low blood sugar is a serious health issue that can be especially dangerous when encountered during exercise. The symptoms of low blood sugar include: nausea, dizziness, extreme hunger, extremity numbness, irritability, rapid heartbeat, headache, confusion, seizures, coma and many others. If left untreated, low blood sugar can result in brain damage or even death. It is because of the risk of low blood sugar that athletes when training eat what appears to be an enormous amount of calories and food. However, because of the excessive amounts of exercise and training they are doing they do not gain weight nor do they lose weight. For example, Olympic gold medalist Michael Phelps consumes 12,000 calories daily while training for 6 hours daily to just maintain his weight. Appropriate amounts of carbohydrates, proteins, and fats are necessary for fuel while exercising but also limit and prevent muscle degeneration during periods of heavy exercise.