Being overweight is a status. Tobacco and alcohol are products. Alcohol also contributes considerably to obesity in itself.

I suppose you could limit it to "sugars" to get an apples to apples comparison. But even so, there's the fact that we do need (some) sugars to live, we can do completely without alcohol or tobacco. And sugar has other uses besides direct consumption, a lot of it goes to alcohol production for biofuels, as well as consumption. Sure the sugar industry causes a lot of harm, but they're not quite as dependent on misery for their profitability - and to the degree they are, it's actually also a lot through alcohol consumption.