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Is My Metabolism Broken?

Despite working out consistently and intensely, plus eating carefully, you’re not losing weight (or not losing it as fast as you’d like or expect). Or you were losing weight consistently…until recently. Now you’re stuck–even though you’re working as hard as ever. Or when you were younger, you were super fit. But now, even when you put in the same effort, you just can’t seem to get as lean.

Can months or years of dieting do long-term harm to the way the human body processes food? Gaining and losing fat can change the way your brain regulates your body weight.

Energy Balance

You need a certain amount of energy (in the form of calories) to stay alive, as well as to move around. You can get this energy from food, or you can retrieve it from stored energy (e.g. your fat tissue).

In theory:

  • If you eat less energy than you expend, you should lose weight.

  • If you do the opposite (i.e. eat more energy than you expend), you should gain weight.

This relationship between ‘energy in’ and ‘energy out’ is called the Energy Balance Equation. While the Energy Balance Equation determines body weight, it doesn’t tell us much about body composition, which is influenced by things like sex hormones levels, macronutrient intake (especially protein), exercise style/frequency/intensity, age, medication use, and genetic predisposition.

Understandably, people get really frustrated and confused with the Energy Balance Equation when the numbers don’t seem to add up, or their results don’t match their expectations. Most of the time, the numbers don’t add up. It’s because the equation is more complicated than it sounds. Many factors affect it. “Eat less, move more” is a good start. That advice alone isn’t enough. It doesn’t take all the complex factors into account.

  • The number of calories in a meal likely doesn’t match the number of calories on the labels or menu. Food labels can be off by as much as 20-25 percent.

  • The amount of energy a food contains in the form of calories is not necessarily the amount of energy we absorb, store, and/or use. Remember that the food we eat must be digested and processed by our unique bodies. The innumerable steps involved in digestion, processing, absorption, storage, and use-as well as our own individual physiological makeup-can all change the energy balance game. You are what you absorb, not what you eat.

  • We absorb less energy from minimally processed carbohydrates, and fats, because they are harder to digest.

  • We absorb more energy from highly processed carbohydrates and fats because they are easier to digest. The more “processed” a food is, the more digestion work is already done for you.

  • We often absorb more energy from foods that are cooked (and/or chopped, soaked, blended) because those processes break down plant and animal cells, increasing their bioavailability.

When eating raw starchy foods (like sweet potatoes), we absorb very few of the calories. After cooking, however, the starches are much more available to us, tripling the number of calories absorbed.

Interestingly, allowing starchy foods to then cool before eating them decreases the number of calories we can extract from them again. (Due to the formation of resistant starches).

  • We may absorb more or less energy depending on the types of bacteria in our gut.

In the end, by eating a diet rich in whole, minimally processed foods, the number of calories you absorb can be significantly less than what you expect. Plus, they require more calories to digest.

Conversely, you will absorb more calories by eating lots of highly processed foods, plus burn fewer calories in the digestive process. (In addition, highly processed foods are less filling, more energy dense, and more likely to cause overeating.)

Energy In = Actual calories eaten - calories not absorbed

‘Energy out’ varies a lot from person to person. ‘Energy out’-again, energy burned through daily metabolism and moving you around-is a dynamic, always changing variable.

  1. Resting metabolic rate (RMR) - RMR is the number of calories you burn each day at rest, just to breathe, think, and live. This represents roughly 60 percent of your ‘energy out’ and depends on weight, body composition, sex, age, genetic predisposition, and possibly (again) the bacterial population of your gut.

  2. Thermic effect of food (TEF) - It takes energy to digest food. Digestion is an active metabolic process. TEF is the number of calories you burn by eating, digesting, and processing your food. This represents roughly 5-10 percent of your ‘energy out.’ In general, you’ll burn more calories in your effort to digest and absorb protein (20-30 percent of its calories) and carbs (5-6 percent) than you do fats (3 percent). As noted before, you’ll burn more calories digesting minimally processed whole foods compared to highly processed foods.

  3. Physical activity (PA) - PA is the calories you burn from purposeful exercise, such as walking, running, going to the gym, gardening, riding a bike, etc.

  4. Non-exercise activity thermogenesis (NEAT) - NEAT is the calories you burn through fidgeting, staying upright, and all other physical activities except purposeful exercise.

Our human metabolisms evolved to keep us alive and functioning when food was scarce. One consequence: When ‘energy in’ goes down, ‘energy out’ goes down to match it. The body fights to maintain homeostasis. Likewise, when ‘energy in’ goes up, ‘energy out’ tends to go up too.

  • Thermic effect of food goes down because you’re eating less.

  • Resting metabolic rate goes down because you weigh less.

  • Calories burned through physical activity go down since you weigh less.

  • Non-exercise activity thermogenesis goes down as you eat less.

  • Calories not absorbed goes down and you absorb more of what you eat.

In addition to these tangible effects on the equation, reducing actual calories eaten also causes hunger signals to increase, causing us to crave more. The net effect leads to a much lower rate of weight loss than you might expect. In some cases, it could even lead to weight re-gain. To add insult to injury, a rise in cortisol from the stress of dieting can cause our bodies to hold onto more water, making us feel “softer” and “less lean” than we are.

For example, research suggests that increasing physical activity above a certain threshold (by exercising more) can trigger:

  • Increased appetite and more actual calories eaten

  • Decreased calories not absorbed as we absorb more of what we eat

  • Decreased RMR

  • Decreased NEAT

The point is that metabolism is much more complicated (and interdependent) than most people realize.

How much you lose or gain will depend on your age, your genetic makeup, your biological sex, if you’ve had relatively more or less body fat and for how long, what medications you’re taking, and the makeup of your microbiome.

This is extra relevant for people who have repeatedly dieted, or for fitness competitors who may repeatedly fluctuate between being extremely lean and being overweight in the off-season.

Adaptive thermogenesis seems to react more strongly or more rapidly with each successive yo-yo of extreme body fat fluctuations.


1. Eat plenty of protein.

  • Protein helps you keep that all-important lean body mass

  • Protein significantly increases satiety, which means you feel fuller despite eating less. (And eating more protein often causes people to eat less overall.)

  • Just by eating more protein you burn more calories, because of the increased thermic effect of food. For example, if you’re eating 2,500 calories daily, 15 percent from protein, 50 percent from carbs, and 35 percent from fats, you’re burning approximately 185 calories per day through digestion. Maintain your total calorie intake but increase protein to 30 percent, drop carbs to 40 percent, and whittle fat to 30 percent, and your TEF goes up to roughly 265 calories per day.

2. Eat a wide variety of fruits, vegetables, quality carbs, and healthy fats.

  • Vegetables are loaded with vitamins, minerals, phytonutrients, water, and fiber to help you fill up during meals, stay full between meals, keep you healthy, and recover from your workouts.

  • The carbs will fuel training, boost leptin (a super important hormone), keep up sex hormones, and prevent feelings of deprivation.

  • And the fats also keep up sex hormones, boost the immune system, suppress excess inflammation, and make food taste good.

3. Adjust your intake as you plateau.

  • As your weight loss progresses, you will need to lower your calorie intake further to continue to progress, as your smaller body will burn fewer calories, and your body is adapting to your diet. (Although I’ve seen this vary also)

  • Weight loss plateaus have less to do with metabolic adaptations and more to do with “an intermittent lack of diet adherence”. In other words, not actually sticking to a nutrition plan consistently.

4. Understand that this is complex.

  • Create an environment that encourages good food choices and discourages poor ones. This can mean making changes to your daily routine, who you spend time with, where you spend time, and what food is readily available to you.

  • Remember that weight loss can and should be relatively slow.

  • This helps to maintain muscle mass and minimize the adaptive metabolic responses to a lower calorie intake and resulting weight loss. Faster weight loss tends to result in more muscle loss without extra fat loss, as well as a larger adaptive response.

5. Do a mixture of resistance, cardiovascular, and recovery activity.

  • Resistance training helps you maintain vital muscle mass, burn calories, and improve glucose tolerance. Cardiovascular exercise improves the health of your cardiovascular system, helps you expend energy, and can improve recovery. But don’t overdo either one.

6. Find ways to increase NEAT.

  • Even small increases in activity can account for hundreds of daily calories, and therefore make a big difference in fat loss efforts.

7. Develop a solid nightly sleep routine and manage your stress. This can help positively impact cortisol levels.

Keep Moving Forward 😊 Sarah

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