Why does milk bloat me when everyone says it is healthy?

The sugar in milk, lactose, needs an enzyme called lactase to be digested. The LCT gene makes lactase, and a nearby control region in the MCM6 gene decides whether you keep producing it into adulthood. Most humans worldwide are programmed to switch lactase off after weaning. Only some populations, mainly Northern Europeans and certain pastoralist groups, evolved to keep it on, which is why so much mainstream nutrition advice assumes milk is universally easy to digest.

In India the picture is mixed. Lactase persistence is more common in parts of North and Northwest India with long dairy traditions, and less common in much of South and East India. So a large share of Indian adults are at least partly lactose intolerant. When lactase is low, undigested lactose travels to the large intestine where gut bacteria ferment it, producing gas, bloating, cramps and sometimes loose stools, usually within a couple of hours of drinking milk.

The takeaway: bloating from milk is normal biology, not a defect, and you are not failing at health. Many people who react to plain milk tolerate curd, dahi, paneer and hard cheese far better, because fermentation and processing lower the lactose. Smaller amounts with food, or lactose-free milk, also help. You can keep dairy in your diet by choosing the forms your gut handles.