As someone who is pretty active in the health/fitness community I HATE n=1 studies like this that get so much press. All this does is give people yet another excuse not to eat a healthy diet and it gets quite annoying.

Of course if you starve yourself of calories you will lose weight, but how sustainable is that in the long term? The reason 90% of diets fail is because people can't keep to them, and who can keep on such a calorie restrictive diet. Never mind the fact that you will be losing muscle mass along with the fat in a starvation type diet like this.

The Calories In = Calories Out dogma, has been ousted out of the hardcore Health/Nutrition community (See Gary Taubes book Good Calories, Bad Calories). The quality and type of foods you eat, i.e the macronutritent ratios, are infinitely more important than the total number of calories. That is not to say that we can eat 10,000 calories of the right food, but you can eat to satiety or to your BMR and still lose weight by eating food that in the right macro ratios.

A diet like the one described here would be destroying this persons insulin sensitivity and in turn his leptin sensitivity. He will be at high risk of Type 2 Diabetes among other things.

If you want to lose weight and get healthy easily, cut your carbs dramatically, eat protein and fat to satiety. Lift some weights and do some slow steady cardio every other day (brisk walk etc.) Fix your sleep hygiene (this is super important) and you will be blown away at how the fat will disappear.