It’s as old as time: The urge to get into better shape in the New Year. Something about a fresh calendar year and a clean slate beckons you to the gym with hopes of new beginnings, healthier living, and maybe even those washboard abs you’ve never quite been able to make happen.

If you’re like the millions of Americans who purchase new gym memberships in January, you may be brimming with motivation right about now— which is great! Ride that wave of willpower. But it’s not just what you eat and how much you exercise that matters; understanding your hormones and how to work with them is a huge part of weight loss success.

Before you embark on your new year’s weight loss plan, get to know the three most influential hormones that are crucial to slimming down— and how to get them on your side.

Ghrelin

Produced in your stomach, ghrelin is your hunger hormone. If you skip a meal, your ghrelin levels rise and make you ravenous, making it nearly impossible for you to resist the next food item you see. For these reasons, skipping breakfast to shave some calories off the day is a big mistake if you’re on the weight loss train; ghrelin is high in the morning after you’ve fasted all night, so you really need to fuel yourself first thing to keep it in check.

And fueling with the right food is just as important as fueling, period: A study published in the journal Clinical Science showed that a high protein meal lowers ghrelin levels significantly more than meals high in fat and carbohydrates. So focus on a high-protein breakfast, such as casein and whey-free protein shakes, and veggie omelettes. And don’t stop at breakfast— aim to get at least 20 grams of protein at lunch and dinner to keep ghrelin low after each meal.

Leptin

Leptin is your helpful sidekick on the weight loss journey; you want no shortage of this hormone if your goal is to drop a pant size or two. It’s an appetite suppressor, telling you when to stop eating. But a little known fact about leptin is that this hormone’s effects in our bodies decrease with age. The older we get, the more likely we are to have leptin resistance, which is when our bodies don’t respond to leptin’s signals (so your brain doesn’t get the message to stop eating). To raise your levels of leptin and increase your sensitivity to this hormone, eat a diet rich in omega-3 fatty acids and boost your intake of foods that contain Eicosapentaenoic acid (EPA), which has been shown to stimulate the production of leptin. Try wild salmon, mackerel, and sardines. Lack of sleep also lowers leptin and increases ghrelin, bringing on the urge to eat more, so be sure to get at least seven and a half hours of shuteye.

Cortisol

Stress and cortisol go hand in hand, and cortisol and belly fat go hand in hand. Anytime you’re faced with a stressful situation, your body pumps out cortisol to meet the challenge. Cortisol encourages your body to hold on to visceral fat— that spare tire around your waist— and it also drives you toward sweet and salty foods to quell the tension you feel (they release pleasure-inducing chemicals in the brain).

To counteract cortisol’s fat-storing effects, cut down on your coffee consumption and steer totally clear of it when you’re feeling stressed. Caffeine taps your adrenal glands to release cortisol, which can be helpful before an interview or big presentation since it sharpens your focus. But when you mix caffeine with stress, your cortisol levels jump higher and stay high for longer.

One study out of the University of Oklahoma showed that consuming 2 and a half to 3 cups of coffee while under mild stress caused cortisol to jump 25 percent— and remain high for 3 hours. Another cortisol-lowering tip: Make it a point to surround yourself with positive people who make you laugh! Simply anticipating a laugh has been shown to lower cortisol levels.

Once you understand how these three hormones work, you can make it easier for your body to drop excess weight, and suddenly your weight loss quest becomes less painful for you. Why starve if it’s just going to raise your ghrelin levels and make it harder to resist bad food choices? And why not find more time for that funny friend if she’s a secret weight loss weapon?

As you move forward with your healthier intentions this year, the most important thing is that you believe you deserve to look and feel better. You deserve that leaner body, a more nutritious diet, a healthier heart, better energy and the many other gifts that come from making and honoring that commitment to yourself. Only good will flow from there.

Here’s to a lean 2015!