Isn't that 1500 calories very low for a Man? I assume its 1500 calories for the duration of the diet ( not intersperesed with higher and lower calorie days )
Just seems very low to me , but if it works for you it works.
Depends very much on your activity levels.
To lose weight you have to have a calorie deficit; ie, you must consume fewer calories than you burn. A pound of body fat has about 3500 calories, so if you have a daily deficit of 500 calories you will lose about a pound a week - which is realistic and achievable.
The British army 24 hour ration packs have about 4000 calories if you consume everything in it. I have done trips in mountain country, walking 15 miles a day with a 12kg pack, and probably burning about 4000 calories a day in the process. Unfortunately my regular job is pretty sedentary (I'm a GP) and my daily calorie burn is around 2000 calories. So the 1500 calorie restriction is not unreasonable when trying to lose weight. Some people go for very low calorie diets of 800, even 500 calories a day but these are generally nutritionally incomplete, not suitable for longer term, can lead to 'yo-yo' dieting, and I am generally not keen on that idea.
A 500 calorie a day deficit works well for most overweight/obese people - you lose a pound a week, or a stone in 3 months or so, but are unlikely to run into any problems.