Metabolism
Everyone talks about how important metabolism is. They're not wrong, it's pretty important. It's impacted by a lot of different lifestyle factors: disease, movement, calorie intake, and more. But what actually is metabolism?
Metabolism powers everything you do like breathing, moving, healing, and growing. It's essentially the amount of energy your body uses to function. There are countless chemical reactions happening in your body constantly that turn the food and drinks you consume into usable energy.
Metabolism works through two main processes. Catabolism breaks down large food molecules into smaller pieces, releasing the energy your body needs right away. Anabolism takes that energy and those smaller pieces and uses them to build and repair tissue, grow new cells, and produce hormones and muscle. In simple terms metabolism is the number of calories your body needs to do everything it does, all day, every day, even when you're doing nothing at all.
There are a few different ways your body uses energy.
Basal Metabolic Rate (BMR) is the energy you need for basic life sustaining functions at complete rest like breathing, your heartbeat, and cell repair. This makes up the majority of what your body burns in a day.
Thermic Effect of Food (TEF) is the energy it takes to digest, absorb, and process the food you eat. Yes, eating itself burns calories.
Physical activity splits into two types. Organized exercise is intentional movement: pilates, running, swimming, strength training, and more. This helps build lean muscle mass, which can support and potentially increase your metabolism over time. Then there's NEAT (non-exercise activity thermogenesis) which is everything else. Taking the stairs, walking around at work, talking with your hands. It adds up more than people realize.
Can your metabolism change? Yes, over time, and for a lot of different reasons.
Ways to support a higher metabolism include eating enough protein, building muscle through organized exercise, and getting enough sleep. Certain medical conditions can also increase metabolism like hyperthyroidism, Graves' disease, type 1 diabetes, fever, infections, and certain cancers.
Metabolism can also slow down. It naturally declines with age so after 60 your resting metabolic rate sees a noticeable drop. Extreme dieting, muscle loss, and rapid weight loss can slow it down too. This is actually one of the reasons chronic restriction backfires. When your body doesn't get enough fuel consistently, it adapts by slowing everything down to protect you, which is exactly the opposite of what most people are trying to achieve when they restrict. When metabolism slows down, it becomes a lot easier to gain weight and a lot harder to lose it. Undereating doesn't support your metabolism it actually increases cravings and the risk of bingeing, which is exactly why undereating can lead to weight gain instead of the weight loss people are chasing. Certain medical conditions can also naturally slow metabolism, including hypothyroidism, Cushing's syndrome, PCOS, type 2 diabetes, and menopause.
The main focus here is supporting and optimizing your metabolism where you can by staying active, building muscle, and managing blood sugar and weight in a sustainable way. Think of metabolism as the engine that turns the food you eat into the energy you need to live. When it slows down, your body physically slows down with it. It won't have enough energy to do what it needs to do like breathe, beat your heart, digest, heal, and everything in between.
If you want support building habits that actually work with your metabolism instead of against it, my Nutrition Toolkit walks you through the balanced plate method, movement, and everything covered here in more detail.
— Ivy ♡
Disclaimer: This blog is for general informational and educational purposes only and does not constitute medical advice, diagnosis, treatment, or personalized nutrition counseling. It is not a substitute for care from a qualified healthcare professional. If you are struggling with disordered eating, support is available through the Alliance for Eating Disorders at 1-866-662-1235.