I think this argument discussion will go on and on until the government removes the food industry from its pockets and starts looking at the facts.
I agree with the posters who said that WW and SW get alot of their money from people rejoining. Surly the fact that so many people have to rejoin says something about those diets, and yes if you lose weight on low carb then go back to eating carbs you will gain weight because that is how your body deals with carbs, it stores them as fat thanks to insulin telling it to. It is a way of eating not a short term fix.
I have done SW, gained weight coz they told me I could eat huge portions of carbs/protein together as long as there was 1/3rd of the plate as veg, and potentially eat as many muller lights as I wanted (all that aspartame, bleurgh).
Did WW successfully but was binging on crap (cakes, chocolate) while still staying in my points because I just craved sweet stuff all the time.
Currently low carbing and wish I had found it sooner. Feel so much healthier, more energy, going to the gym 3 times a week for hard workouts and managing fine with energy levels.
In evolutionary terms we evolved to eat meat, veg, fruit (seasonally, so not huge amounts), nuts and naturally occuring fats. we did not evolve to eat grains (whole or refined) or sugar. Our body's desired fuel for energy is fat, and although some organs do need a very small amount of carbs to function, the amount needed can be assimilated by the liver from protein in the diet via gluconeogenesis. Our bodies therefore have an natural inbuilt mechanism for living on a low carb diet. Bear in mind that gluconeogenesis will only occur if no carbs in the way of veg are being consumed.
I eat Paleo which is how we evolved to eat and in my opinion is the healthiest way to eat. It is not dissimilar to other low carb plans.
My DH has been eating low carb for a while and his IBS symptoms have dissappeared yet if he eats any processed carbs they come back with avengeance.
My body composition is alot different on low carb than low fat too. There are alot of "skinny fat" people around who may be a size 8 but probably have a high % of body fat and less muscle because low cal/low fat diets have been shown to promote muscle loss aswell as fat loss but low carb promotes fat loss only.