Highly individual. Do you need to avoid it to lose weight? No, you don't. Fat loss is about being in a caloric deficit. You can still eat fat and lose fat if you're in a deficit. Dairy is one of those things that will vary with each individual. Some people have lactose issues, myself included. I've cut it out just because my stomach effing hates me when I consume it. However, it wouldn't hinder my fat loss efforts should I decide to eat/drink it. If you're not lactose intolerant, do whatever you want. However, many don't know they're lactose intolerant until they eliminate it for about a month and then reintroduce and see what happens. Highly, highly individualized here.
iForce Nutrition Representative - iTrain. iCompete. iDominate
You know when you are lactose intolerant in about an hour after you eat it dont need a month for that..lol
Now what causes ppl to be lactose intolerant sometimes is another food they eat like gluten for example which interefers with normal digestion and certain enzyme production.
Even then it's not a certainty. Introducing (or re-introducing) ANY major dietary change will elicit the "body no likey" response at first. Any change at all. Whatsoever. Even if the change is 100% salubrious in the long run.However, many don't know they're lactose intolerant until they eliminate it for about a month and then reintroduce and see what happens.
Like, if you've been Super Sizing Me for the last five years and suddenly you start throwing down tons of whole foods and fresh vegetables, you'll feel HORRIBLE for a couple of weeks. Gas, more gas, lethargy, diarrhea, maybe nausea... the whole 9 yards. Does that mean you're "vegetable intolerant"? Most likely not, it just means you are adjusting to a big delta.
This is also the reason lots of people get sick/diarrheic when traveling abroad. Sometimes it's the sketchy stuff in the water, but 9 times out of 10 it's just the result of eating foods that make your body say, "whoa wut".
This is not to say that lactose intolerance isn't a thing; clearly, it's a thing. Rather, this is just a warning against being a hypochondriac when it comes to nutrition. If something is really a problem, you should test it beyond just eliminating and re-introducing—unless it's a food that you don't like very much, and so can eliminate from your diet without much ado.
I.e., don't be That Guy who suddenly starts mortifying his friends by insisting on gluten-free vegan non-dairy hemp-based love&light&chakra&etc. meals at restaurants... unless you are actually the 1 in 1,000,000 who actually needs that.