Well, thats a tough one. Its true that some of todays clothing items are more smell-resistant than they used to be, but there are limits. Most of you remember that dark blue long underwear that was so prevalent in the 1980s. With that stuff, bad smells would chemically bind to it like hydrogen to oxygen molecules. Whew. Nasty.
Ive never done an extended stink-proof test on my Icebreaker stuff. Over the course of a few days it always seems fine, and it is billed as naturally odor-resistant. It doesnt have an anti-microbial finish, but the merino wool isnt prone to absorbing odors. Thats due to several factors. For one, wools ability to absorb moisture keeps the skin drier, so the microbes dont find as much moisture in which to grow. Its texture and subatomic charge is different from synthetics, so it doesnt tend to attract odor-producing bacteria. And its able to hold" bad smalls and release them in the wash, rather than releasing them all the time.
Icebreakers lightest piece is the Bodyfit 150 Atlas Tank ($40), a sleek, sleeveless piece that would work well in hot weather.
Some fabrics also employ add-on odor-defeaters. Patagonia, for instance, uses a process it calls Gladiodor," in which natural amino acids added to the fabric coating basically eat bad smells. Find it in the Capilene 1 Crew for $38. Some of Marmots base layers like the Lightweight LS Crew ($39) use natural cocona fiber, which is billed as naturally odor-fighting.
But nothing is perfect, and in time you will smell. Take two base layers if you can, and keep one as dry as possible while exchanging them daily. And wash things out in water when you can. In time, you will embrace the naturalness of it all.