Alcohol in beverages comes from fermentation of sugars or starch; thus the higher the alcohol content, the higher the calories.
As for expanding waistlines, one should check their eating habits and lifestyle. Just because beer is such a good match for different types of food, one should not be too quick to blame the beer. Here is a bit of reality check:
Standard serving: beer/regular cola/soda = small can;
table wine = single serve small bottle;
spirits/liqueurs = miniature mini bar bottle;
milk/apple juice/orange juice = small tetrapak
