Want to shed some pounds for your health? (Same.) Or maybe you just want to fit into your fave pair of jeans again. (Also same.)

No matter why you want to lose weight, it’s important to know the science behind fat first. Here’s the 411 on fat.

There are thousands of diets that claim you’ll lose, like, 20 pounds in 3 hours. But the easiest (and prob most effective) weight loss formula is to consume fewer calories than you burn. This is called a calorie deficit.

There’s no exact amount of calories you need to cut back on to lose weight. Numbers vary from person to person. But a 2011 study showed that a 500-calorie-a-day cutback is a good start.

PSA: Starvation is never the answer. Your body needs food to function.

You can lose more weight if you maintain a nutrient-rich diet and a solid exercise routine, according to a research review. So, if you want to shed fat you have to move it, move it.

A 2013 research review showed that exercise increases blood flow to fat cells and muscles, releasing fats faster and increasing how much energy you burn.

For the best of both worlds, try combining cardio (burns calories) with resistance training (increases muscle mass).

Some killer cardio routines can include:

Some examples of resistance training are:

Fat cells don’t disappear, they shrink in size. Here’s the lowdown.

Byproducts of fat loss

When body fat is broken down and turned into energy, carbon dioxide and water are released. These are fat loss byproducts.

You exhale the carbon dioxide when you breathe and the H2O is flushed out when you pee, sweat, or exhale. According to a research review, these bodily byproducts increase when you exercise since you breathe and sweat more during a workout.

Where do you lose fat first?

Sometimes you may want to zap the fat in a specific area. (Hello abs my old friend, I’d love to see six of you again.) But one 2011 study showed that spot reduction — losing weight in a particular area — isn’t that easy. It’s similar to when you gain weight. The fat might hit your tummy, butt, or chin.

Some peeps lose weight from certain areas of their bods more easily than others. It usually boils down to lifestyle and family history. A research review showed that genetics can play a big role in body fat distribution.

FYI: A research review showed that body fat placement can evolve over time due to changes in fat cells.

Why is maintaining weight loss so hard?

A research review showed that fat cells multiply and get bigger when you eat more calories than your body can burn. The cells can shrink, but they don’t disappear completely. A study with animals showed that this might be why maintaining weight loss can be annoying AF.

The same basic number of fat cells are still there even after you lose weight — and keeping them honey-I-shrunk-the-cells status can be a challenge.

Your weight loss timeline depends on a ton of factors like:

Keep in mind: Weight loss is a marathon, not a sprint. Dropping 10 pounds in a week is almost never a good idea. In fact, one 2011 study showed that rapid weight loss can come with a lot of risky side effects like:

That fad diet you saw on TikTok just isn’t worth it, fam.

Plus, one study suggested that losing weight at a slower place can help you keep it off long-term. But more research is needed to prove this 10/10.

Reminder: Fat is NOT the enemy. Your body needs fat for fuel. We all wish we could snap our fingers Thanos style and have our dream bod. But please know, your body is absolutely beautiful just the way it is.

But if you want to lose weight for health reasons, we’re here for it. Just remember to be patient with the process and be kind to yourself.