Recently I saw this question on Quora: "What are the diets to follow if I want to lose 15 kilos in 5 months?". While I am strongly against "taking up diet only to lose weight and then forget about it" syndrome (say hello to Yo-yo effect), it still can be calculated ;)
Anyway,a little bit of math (assuming daily calories consumption at 2000).
1 kg of body fat is around 7700 kcal. It means that we have to cut or burn
7700 calories above usual needs in order to lose one kilogram.
15 kg in 5 months means losing 3 kg per month and that means cutting around 700 kcal per day. This would be more or less 1/3rd of assumed daily consumption (without exercise).
In my opinion, 1300 kcal diet is far from healthy, no matter what we eat. Also, any diet is difficult to follow when we are constantly hungry. On the other hand, losing 10 kg in 5 months means cutting / burning around 500 kcal per day, which is more reasonable and healthy.
Think about that.
In terms of actual diet, I'm big advocate of paleo diet, known also as caveman diet. Basically we can eat everything that caveman could have eaten. Meat, fish, fruit, vegetables, nuts, all natural ingredients, no processed food. Cut bread, white pasta and white rice and if you need to, add some full grain products instead. Don't drink soda, don't eat fast foods and be reasonable with alcohol. And lastly - do not starve yourself!
Of course, it won't work if we exercise few times per week, when our calories consumption is much higher.
Original Quora question is here