An Easily Digestible Guide To Hunger Hormones & Energy Balance

Fad diets come and go, but one popular phrase used (way too often) is "eat less, move more." 

At some point in your life, you've probably heard some "expert" drone on about energy balance and cutting calories to lose weight. It's important to be aware of where energy (aka calories) comes from—e.g., food, drinks, and even some supplements—and it's equally important to consider how we burn energy. But energy balance and metabolism are more complicated than that.

While the "calories in, calories out" adage around healthy weight maintenance is outdated, it's not because it's wholly untrue. Rather, this overused cliché is vastly oversimplifying human metabolism.

The first is resting energy expenditure (REE), a measure of the number of calories a particular body (i.e., it's personalized) burns while at rest. This is the "burn rate" to simply "keep the lights on" for major physiological functions (you know, the billions of cellular pathways that make up cellular, tissue, and organ function). I'm talking about making sure your organs are all doing their jobs (i.e., your lungs are breathing, your heart is beating and circulating blood, your gut muscles are helping digest food, etc.), which is no small feat. 

Your REE makes up 60 to 75% of the energy your body uses while at rest and is built into the more commonly known basal metabolic rate (BMR), which is affected by factors like age, sex, and activity level.

This next factor that affects your daily energy expenditure may seem obvious: The intensity and frequency of your movement each day (all movement counts!) plays a huge part in how many calories (i.e., how much energy) you burn each day.

By the way, when it comes to expending energy (i.e., burning calories), there's one type of physical activity that reigns supreme: weightlifting. Lifting weights is an effective way to increase skeletal muscle mass, and skeletal mass burns more calories when the body is at rest than other tissues (like adipose tissue, aka fat).

The third component of energy expenditure is the thermic effect of food, aka thermogenesis. Simply put, it's the process of heat generation that occurs for several hours after we consume food, drinks, and even supplements. Thermogenesis increases metabolic rate to help the body digest, absorb, and store nutrients and is thought to expend about 10% of the energy needs estimated by a BMR.

Leptin is an adipokine hormone produced by fat (adipose) cells. As a neuroendocrine hormone, one of its jobs is to communicate with the brain to maintain balanced fat stores. If there's enough energy stored in fat, leptin messages the brain that the body doesn't need to consume as many additional calories (energy). Ideally, the feedback response of the brain should cue a feeling of fullness.

According to registered dietitian Erin Skinner, M.S., R.D., LDN, IFNCP, simply increasing leptin levels should not be the goal when trying to maintain a healthy body composition. "The energy deficit caused by eating less and/or exercising more [paradoxically] lowers leptin, which increases appetite," Skinner explains. (One of the many reasons maintaining weight loss is challenging.) Instead, people who struggle with maintaining a healthy weight should focus on a diet that improves leptin sensitivity.

Most of us have heard of the term "insulin sensitivity" when it comes to achieving blood sugar balance, aka glycemic control, throughout our days and life. But fewer of us are thinking about optimizing our leptin sensitivity. "Leptin homeostasis is an active area of research, and guess what's a critical factor? Nutrition for the win! Healthful dietary patterns can help us regain leptin sensitivity1," Ferira shares.

Ghrelin (or as I like to think of it, growlin') is the hunger hormone. This orexigenic (fancy word for appetite-stimulating) neuroendocrine hormone is released when the stomach is empty and stops when the stomach is stretched. It's highest before eating and lowest after eating.

"Ghrelin is one of the most tangible and fascinating examples of the gut-brain axis, and its daily flux is directly tied to our appetite regulation and food consumption patterns," Ferira explains.

Some people may not experience the same reduction in ghrelin levels after a meal (i.e., postprandial ghrelin), which can leave them feeling hungry more often despite eating adequate food. What's more, a person with a healthy (i.e., active) metabolism that ignores or misses ghrelin's cues may experience a decrease in overall energy expenditure.

So, how can you learn to tune in to your body's hunger signals? Working on mindfulness around hunger cues can take many forms. One way to start is waiting about 20 minutes after your first helping of a well-balanced meal and then reflecting on whether you feel satiated.

Other hormones worth mentioning, which Ferira alluded to above, include adiponectin (a specialized adipokine hormone that promotes fat burn and healthy blood sugar levels), cortisol (the infamous "stress" hormone), and thyroid hormones (aka the "master metabolism" hormones).

I definitely do not recommend hearkening back to the days of diet pills—this isn't 1999, after all. Today, leaning into scientific innovation and the wonderful power of plants, a new age of beneficial botanicals are available to support metabolic adaptation in a healthy, holistic way. Tools in the broader toolbox (beside metabolic-healthy habits like balanced nutrition, physical activity, and good sleep), if you will.

Some of these plant-based bioactives we can leverage to support a healthy metabolism include veld grape, green tea extract (particularly, its catechin EGCG), cayenne pepper (aka chili pepper), and caffeine.* These botanicals work through diverse pathways in the body to help regulate leptin and adiponectin levels, increase your resting energy expenditure, activate brown fat tissue (the type of fat that burns calories), and enhance how well you utilize energy to promote overall metabolic health and efficiency.* 

I cannot stress this enough: Inadequate sleep and poor sleep quality are the root of so many metabolic health concerns. Aiming for seven to nine hours of quality sleep is a foundation of a healthy metabolism and overall well-being. In fact, insufficient sleep time and quality are associated with both increased ghrelin (remember, growlin') and decreased leptin (fullness cue) levels, among a slew of other whole-body health concerns.

Naturally, some people love working out. Others…well, not so much. Finding a type of movement that brings you joy is key and will encourage you to consistently choose action over inaction. If you can work out with a friend for accountability, even better!

That said, certain types of physical activity are certainly more efficient at burning calories (i.e., expending energy). According to Skinner, the best exercise plan for a healthy metabolism is to exercise around 150 minutes per week with an elevated heart rate, mostly in zone 2 (i.e., approximately 60 to 70% of your maximum heart rate). This may include weightlifting, dance classes, Pilates, fast-paced walking, or jogging. Hot girl walk, anyone?

Incorporating muscle-building exercises two to three times per week is also instrumental for balancing your metabolism, supporting healthy blood sugars, and increasing calories burned (even while you're resting). 

One warning to heed: It's thought that too much high-intensity or endurance/cardio exercise can actually make your metabolic health worse, so balance your efforts with lower-intensity walking and other low-impact activities throughout the week to give your muscles a chance to recover.

You may be familiar with New York Times bestselling author Michael Pollan's famous quote: "Eat food, not too much, mostly plants." This is a great baseline strategy to work on your metabolic health; however, I worry people will perceive it as encouragement to undereat.

It's not uncommon for people with a slow (i.e., less active) metabolism to also experience fluctuating or dysregulated blood lipid and blood sugar levels.

A simple and easy way to support healthy blood sugar and lipid status through nutrition is to make half your meal nonstarchy vegetables and divide the remaining half between starches (e.g., sweet potatoes, wild rice, fruit) and protein (plant-based or animal-based), plus 1 to 2 tablespoons of a healthy fat (think olive oil, grass-fed butter, avocado, or nut butter). 

In the fast-paced world we're living in, meals that are both calm and focused can feel like a distant memory. Not slowing down to look at, smell, thoroughly chew, and savor food is where many people begin to lose touch with their appetite cues.

"Mindful eating practices are incredibly useful when it comes to honing our appetite regulation," Ferira says, adding that, "by savoring our food, we can be more in touch with a built-in hormonal symphony that's intuitive. Give your body a chance to talk back!"

Mealtime looks different for everyone and can vary based on when you eat. When it comes to timing, each person will have to experiment to figure out what works best for them at each stage of their life.

While not right for everyone, intermittent fasting with a 12- to 16-hour fasting window has been shown to improve body composition, metabolic markers, and even longevity. There are certain health concerns that may not benefit from especially tight windows of intermittent fasting, so working with a knowledgeable health care practitioner who's intimately familiar with your unique history and health needs is always recommended.

Tuning in to your hunger signals is also affected by who you're sharing your meals with. People who aren't aware of their own cues or distract you (we see you, parents!) may make it more challenging to sense your own hunger and fullness, while people who have figured out their own magic metabolism method may be able to pass on some tips and help you to learn new, healthy eating patterns.

Hormones and metabolism are complex, but there's so much within your control.

If you're confused about your own hunger cues or struggling to tune into them, you're not alone. Consider partnering with an integrative health care provider who understands hormones and can help you get to the root of your metabolic concern, so you can take the right steps to correct the course of your metabolic health.