You are indeed both correct. The problem with people who do things like drink 2 litres of coke, is that they become insulin resistant. Meaning they produce a

You are indeed both correct. The problem with people who do things like drink 2 litres of coke, is that they become insulin resistant. Meaning they produce a lot more insulin than required, as thier bodies ability to gauge how much insulin is thrown out of wack (by the spikes in sugar). Now when you have something that only requires 2units of insulin, your body outputs 4 (because of insulin resistance) and now fat cells are being created when they shouldn't be. (Because insulin is what regulates fat storage, i.e insulin takes the sugar out of your blood by shoving it in a fat cell). Keep this up, and you eventually end up diabetic. You are both saying the two different sides to the same coin. EDIT: To be clear - If you have regulated insulin (by controlling carbs and suger) you will gain less fat (but lose it normally). If you starve your body of those sugars in the first place you will lose more than you gain (regardless of insulin). This is why WeightWatchers works, and why Excercising your arse off works, and also why Paleo/Atkins/Low-carb works.