If you are talking about the smell of sweat rather than the smell of BO which is stale sweat, then yes, it can change. I happen to have a very sensitive nose - (this is by training btw, I am not special and anyone can develop a sensitive nose by simply learning how to do so) because my lifelong hobby is perfume and scent. I used to create fragrances for toiletries commercially.
I am a low carber by preference - it suits me, always has. My body smells quite different when I very low carb than when I have periods of eating carbs. It isn't just my sweat, it is in my pee (smells like popcorn when I am very low carbing!) and even in the taste of my mouth.
In addition, eating certain types of food such as alliums or red meat will change body odour significantly, as does excessive dairy consumption. I am not alone in being able to distinguish someone with a plant based diet from a carnivore simply by smell...
And, more to the point, so does taking certain drugs and vitamins. B Vitamins for example, can drastically change body odour - I often see posts on here where people complain that their pee is smelly and it is very possibly due to vitamin supplements, for example those aimed at hair loss which are popular with dieters and which contain very high doses of certain vitamin Bs. In addition, many so-called protein supplements also contain vitamins.
I can't say that I have noticed MJ in and of itself changing my body odour, but I wouldn't rule it out. Body builders anecdotally speak of body odour changes, and whilst it is tempting to dismiss this as purely due to dietary changes, it may well not be the only reason. I haven't seen any scientific studies on the subject of MJ so there is no definitive evidence either way and no-one can say for sure.