Uniqlo has a line of undershirts and clothing we swear by that's incredibly thin and incredibly warm - and most of the styles are only $15

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• Staying warm during the winter can be tricky without wearing a bunch of heavy layers, but Uniqlo's HEATTECH fabric is the best way to stay warm without the bulk.
• HEATTECH is made of a special blend of materials that wick moisture from your body and turn its kinetic energy into heat.
• I've been wearing HEATTECH clothing from Uniqlo for many years, and I've found it's warmth-for-weight ratio to be the best of any under-layer I've tried.
• It's also pretty affordable - most basic items are priced at $14.90, heavier pieces are priced at $19.90, and apparel like jeans and dress pants priced at $49.90.
• Uniqlo HEATTECH is available for men and women.

Effectively dressing for cold weather is very easy to get wrong. Putting on layer after layer after layer and your biggest, bulkiest coat is a sure way to make everyday activities like commuting or even just running out for lunch a massive headache. Even if you're warm (perhaps too warm), you end up feeling encumbered by those layers and walking like a penguin.

I absolutely hate the cold, and living in the Northeast, I know these problems all too well - but Japanese clothing brand Uniqlo has been the source of my most reliable fix for many years. Rather than attempting to block out the cold by piling on all my warm clothes at once, Uniqlo keeps me warm with its single thin layer of heat-retaining fabric called HEATTECH.

Made from a special blend of rayon, polyester, and acrylic, HEATTECH wicks your body's moisture into the fibers and converts its kinetic energy into heat. Air pockets within the ultra-thin fibers trap the heat and retain it. The result is a lightweight layer of warmth without the bulk.

I first started shopping at Uniqlo around 2009, which was well before they had locations all over the country. Living in central New Jersey, the closest store to me was all the way in Manhattan, but the affordable prices made it well worth the trip. It was then that I came across the HEATTECH clothing - and I've been buying it ever since.

The first HEATTECH pieces I bought were a long-sleeve crewneck and a pair of tights to wear underneath my clothes during the winter. Although it's been so long since I first tried them, I vividly remember being disappointed with how thin they were, assuming that they wouldn't be effective for staying warm. After wearing them, I was pleasantly proved wrong. The material's heat retention is noticeably better than normal waffle-knit thermal long johns.

The Uniqlo HEATTECH line has come a long way since I first began wearing it. What started out as a few pieces of undergarments has evolved into a thorough selection of apparel that you could theoretically dress in from head to toe. The collection includes undershirts, underwear, long johns, leggings, tank tops, sweaters, hats, gloves, jeans, and even a collaboration with fashion designer Alexander Wang. Of the many options, some of my other favorites pieces are the tech-friendly gloves and the slim-fit jeans.

Most HEATTECH styles are offered in three different warmth levels including regular HEATTECH, extra warm, and ultra warm for those unbearably cold days. Another great attribute is that all the prices are very fair. Nothing will cost you much (if any) more than comparable cotton garments.

I'm not the only one on the team who swears by the technology for cold weather. Here's what Insider Picks VP Breton Fischetti, had to say about his experience wearing HEATTECH clothing:

I discovered Uniqlo HEATTECH clothing while I was walking around the Uniqlo store on a cold day. I decided to buy a piece to see if it would be any different from the thermal layers I was used to, and I was really surprised by how effective it was. I now have HEATTECH undershirts for the winter and a HEATTECH sweater. They hold in so much heat that I feel comfortable even on the coldest days. HEATTECH doesn't stop wind, so if it's blustery, you'll still need a wind stopping layer, but for fighting the bone-chilling cold, HEATTECH is my go-to. It's also great in the spring when you're sick of wearing a jacket because it feels like having two layers on at once.

If you've been struggling to find layers that are warm and bulk-free, Uniqlo's HEATTECH styles are a great solution.

Shop the men's Uniqlo HEATTECH Collection here.

Shop the women's Uniqlo HEATTECH Collection here.