All weight loss programs that recognize a few basic, yet important principles of proper weight loss can be effective. These principles include: - Exercise (not appetite) should be the "primary" strategy for controlling body weight and increasing health. - Eating habits must be adjusted not only to ensure weight loss, but also to ensure adequate nutrition. - Fat loss will slow and eventually stop on any weight loss program. Of course, when trying to apply these principles to each individual, some concessions and a little creativity may be needed to reach goals and overcome plateaus. You should count calories for at least a week to establish what your caloric intake is (99% of the dieters over- or underestimate this), and your macronutrient ratios. - Create a caloric deficit. 10-12kcal/lbs works great for most people. 14-15kcal/lbs may be better for someone with a high activity level during the week. - Eat 1g/lbs of bodyweight in protein. - Get 25% of calories from fats, mostly EFAs. Aim for 1-1.5lbs/week of weight loss. If you lose more and notice your strength decreasing, you may be sacrificing muscle and should increase calories. Basically, you just have to: 1. Meet certain requirements: caloric deficit, protein, EFA's. That's required of any diet, no matter the interpretation. 2. Figure out the rest of the diet dependent on the person. If they are active, have decent insulin sensitivity, and enjoy eating lower GI carbs, a moderate to higher carb diet will probably be sufficient. Something like 50/25/25 or 40/30/30. If they are very inactive, highly insulin resistant and/or simply won't remove the high GI crap from their diet, reducing carbs further or removing them competely may be the only workeable approach to get calories/hunger under control. So there's what's required (deficit, protein, EFA's) and there's what's optional (everything else). What's required isn't up to debate: it applies to everyone. What's optional depends on the needs of the person. The ease with which a person loses weight depends on several factors. Some of these factors include: Body size (height, frame size) The amount of lean mass (muscle) a person has Hormone levels Without going into too much detail, the bigger you are the more calories you burn in a day. Likewise, the more muscle you have the more calories you burn. So the bigger and more muscular you are, the easier it is to lose weight. Hormones like estrogen can make losing weight much more difficult. testosterone, on the other hand, facilitates fat loss. This alone can account for some of the differences seen between men and women. Additionally, thyroid hormones play a major role in regulating body weight. If you have been "sort of dieting" for a long time, your thyroid levels may be reduced. The only way to get thyroid levels optimized for fat loss is to refeed yourself with more healthy food and calories for a couple weeks before attempting to diet again. Blood tests may also be helpful in detecting hormonal deficiencies that may hinder weight loss.