For this writer, going dairy-free led to weight loss, clear skin, ​and more energy.
lactose intolerant
Bright green broccoli in an ice cream cone with sprinkles.
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A few years ago when I went home for the holidays, I asked my mom if Santa could bring me some TUMS. She raised an eyebrow. I explained that lately, after each meal, I was taking a TUMS. Or two. Maybe three—tops.

My mom is a yogi and a health nut. Naturally, she suggested I change my diet, specifically that I consider giving up dairy. (After all, dairy *can* be difficult to digest for some people—more on that later.) I would feel better if I ate the right foods, she told me. (Related: Is Dairy Healthy? The Pros and Cons of Consuming Dairy)

I'll admit it: My diet wasn't perfect. While I exercised regularly, limited my drinking, and had a mostly balanced diet of veggies and meat, I also splurged—a lot. I'd always got cheese. At a Mexican restaurant, I'd never say no to queso dip. I thought my exercise routine would take care of the dairy slip-ups, but unfortunately, that wasn't working (you can’t out-exercise a bad diet, nor should you try).

Not only was I bloated, lethargic, and acne-prone (food can be an acne trigger), I had also gained nearly 10 pounds. My 5'4" frame was holding almost 165 pounds. I was uncomfortable. (BTW: Weight gain isn’t *always* a bad thing—these 11 women have gained weight the healthy way and are happier than ever.)

So I took my mom's advice in giving up dairy and decided to do Whole30, which calls for you to cut out dairy, booze, refined or processed sugars, legumes, and gluten for 30 days, then gradually add those foods back into your diet and see how your body responds. (Related: 20 Whole30 Recipes for Breakfast, Lunch, Dinner, or Snacks)

For the most part, everything went smoothly. After 30 days, I added wine and rice back in and felt fine. It wasn't until I had a protein shake with skim milk in it that I noticed a huge change. After drinking it, I vomited.

See, lots of people are sensitive to lactose—a sugar present in milk and anything made of milk. And after seeing a doctor, I found out I'm intolerant to it. (Related: 5 Genius Dairy Swaps You’ve Never Thought Of)

About 30 million Americans are lactose intolerant, which means they develop bloating, gas, and diarrhea when they eat lactose because they lack the enzyme needed to digest lactose.

Of course, lactose intolerant people don't always need to give up dairy *entirely*. Yogurt and hard cheeses contain very little lactose, for example. Some lactose intolerant people can even consume a serving of dairy without symptoms, says Susan Barr, Ph.D., R.D., a professor of nutrition at the University of British Columbia.

But that day after the protein shake, I gave up dairy.

Giving up dairy hasn't been easy, but the changes in my body (I've lost 25 pounds!), energy levels, and overall life have been incredible.

Of course, this is just my story. "People should not eliminate any food unless they have really good reasons," says Paige Smathers, R.D.N., a dietitian based near Salt Lake City, UT. "If you're cutting something out, you should really know it's essential and not a guess because it's potentially setting you up for some difficulties nutritionally and otherwise."

That said, there are four big ways giving up dairy has made me healthier.

I’ve lost weight and never bloat.

Smathers says there’s some research suggesting that dairy products are actually helpful with weight loss (think: protein-rich Greek yogurt, even cheese). Plus, the calcium in dairy can be crucial if you're trying to drop pounds. "As you lose weight, you can also lose bone," says Barr. "If you have sufficient calcium intake during weight loss, that can reduce the impact on bone density." Of course: "You do get calcium from broccoli or kale," adds Barr. And these amazing sources of calcium perfect for vegans can also fill you up.

Plus, a few years ago, I was so bloated could barely wear jeans. Over the course of the day, my stomach would expand so much from everything I ate (wake up feeling bloated? Here’s what to eat). Since giving up dairy? My tummy stays pretty flat all day long—even after lunch. While I used to grab a half-sandwich and soup, now I make sure my lunch has lean meat, veggies, and fruit.

I kissed PMS goodbye.

Awful period symptoms before my cycle started used to be something that happened on the reg. My breasts would also swell up—perhaps due to the estrogen in most milk and cheese products (after all, dietary choices *can* be one of the things making your PMS worse).

While it might seem insane to think that giving up dairy and my beloved Brie could make such a difference in my lady parts, these days I rarely have PMS. In fact, I'm often surprised when my period comes because everything stays just the same.

I look forward to the gym.

By the time 6:30 p.m. rolled around in years past, I would find myself feeling pretty gross, and I'd often find excuses for why I didn't want to exercise. Even if I did make it to the gym, I wouldn't give 100 percent and I hated how I looked.

After giving up dairy? I also got rid of that feeling I used to have at the end of the day. Now I work out five days a week—and I actually look forward to it. I fell in love with boxing (it *can* be life-changing), boot camp-style, and high-intensity interval training classes, and I've mastered the yoga headstand.

My strength is up and so is my confidence: I make it out on more dates, I'm always up for a 5K with friends, I don't need my knees to do push-ups anymore, and I love the way I feel drenched in sweat. (Related: 10 Ways to Fall Back in Love with the Gym)

My acne is gone.

I've always had acne-prone skin, and though I went on Accutane a few years ago, I'd still suffer occasional breakouts (BTW, these are the spot treatments derms swear by). I never really thought much of it, until giving up dairy. Then, I noticed I'd get a breakout once a month—if that.

By letting go of my cheese-and-meat-and-crackers snack and trips to the frozen yogurt shop, I've been able to wear less makeup, and I've even noticed my blue eyes to be even brighter.

I'm happier.

One of the best realizations that has come from giving up dairy? How great I feel when I put the right things into my body—and how terrible I feel when I don't. While we all splurge now and then (we're human, it's allowed!), I don't crave unhealthy food as often as I did before. And though there are things I miss—hot fudge sundaes and steak and cheese quesadillas, ahh—I love how I feel without them more. (Related: 6 Foods to Fix Your Mood)

Additional reporting by Julie Stewart.