Can eating too little actually damage your metabolism?

Your food intake is the ultimate determinant of the amount of energy you burn up. But how much energy do you really burn up? During a typical day, you burn through a minimum of 3000 calories, and most people burn up more than that. You will be surprised to learn that, if you are eating less than the minimum, it is possible that you are actually burning more calories than you think!

You may have heard about caloric restriction previously, but have you actually heard of caloric restriction’s negative effects on the body? A number of recent studies have found that consuming less than one thousand calories a day can decrease metabolism and make it difficult to maintain healthy weight. So, is eating less bad for you?

At first glance, this may sound like a ridiculous question. But the truth is that undernutrition can have serious consequences. One study found that calorie restriction, or eating less than your daily caloric needs, caused metabolic changes that could lead to chronic diseases. To make matters worse, recent research has indicated that some people respond to eating less than the recommended daily allowance by entering a state of chronic undernutrition known as “starvation mode”. This happens when the body starts burning its own stored resources – like muscle tissue – in order to survive. As a result, the body heats up, and may in fact die of starvation.

In the fitness industry, there’s a lot of debate over whether crash dieting may harm your metabolism. In this post, we’ll look into this fascinating subject and sort out the truth from the fantasy. We’ll also explain why crash diets may make it difficult to maintain your weight in the long run.

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You’re not losing weight (or not losing it as quickly as you’d want or anticipate) despite working out regularly and hard and eating wisely.

Alternatively, you were regularly losing weight… until lately. Even if you’re working as hard as you can, you’re stuck now.

Or maybe you were extremely fit when you were younger. Perhaps you competed in fitness contests. Perhaps you tried some fad diets. But today, even if you put in the same amount of work, you can’t manage to become as slim as you used to.

“Has my metabolism been harmed?”

This is a question that our coaching clients often ask.

(If you work in health, fitness, or wellness, you’ve certainly heard the same thing from your customers or patients.)

Can months or years of dieting affect the way the human body processes food in the long run?

No, not at all.

Gaining and losing weight, on the other hand, may alter the way your brain controls your body weight.

Let’s look at how human metabolism works to have a better understanding of the solution. Then we’ll discuss whether or not the metabolism can be harmed.

Note: The physics of energy balance, thermodynamics, and metabolic control is discussed in this article. Feel free to go further if you like learning new things.

If, on the other hand, you’re just searching for reliable, research-backed guidance on how to lose fat and break through weight-loss plateaus, skip to the conclusion. 

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The principles of physics still apply to energy balance.

To remain alive and move about, you require a specific quantity of energy (in the form of calories). This energy may come from food or it can be retrieved from stored energy (e.g. your fat tissue).

Theoretically:

• You should lose weight if you consume less energy than you exert.

• You will gain weight if you do the reverse (consume more energy than you burn).

In other words: *We use the term “body stores” deliberately as it represents the tissues available for breakdown (fat, muscle, organ, bone, etc) and excludes water (which can change body weight independently of energy balance).

The Energy Balance Equation is the most widely recognized model for estimating a person’s energy balance and how much weight they’ll lose or gain over time, and it’s based on the connection between “energy in” and “energy out.”

The Energy Balance Equation predicts body weight but not body composition, which is affected by factors such as sex hormone levels, macronutrient consumption (particularly protein), exercise type / frequency / intensity, age, medication usage, genetic predisposition, and more.

When the numbers don’t add up or the outcomes don’t match their expectations, it’s understandable that individuals get irritated and perplexed with the Energy Balance Equation. (By the way, this is an excellent lesson on the necessity of modifying your expectations to meet observed reality.)

And it’s a legitimate source of annoyance. In most cases, the numbers don’t add up.

Importantly:

This discrepancy between expectations and reality is not due to a flaw in the Energy Balance Equation or a fiction. Even though it seems that way at times, no one’s body defies the rules of physics.

It’s because the equation is trickier than it seems.

The Energy Balance Equation is influenced by a variety of variables that are not mutually exclusive. What you do with ‘energy in’ has an impact on ‘energy out.’ And the other way around.

A excellent place to start is with the phrase “eat less, exercise more.” (It’s likely that most of us might benefit by eating a bit less and doing a little more daily exercise.)

That counsel, however, is insufficient. It doesn’t account for all of the interconnected, complicated variables.

Let’s look at some of these variables, beginning with the ‘energy in’ portion of the equation.

‘Energy in’ is more difficult than you would imagine.

Reason 1: The amount of calories in a meal will very certainly differ from the number of calories shown on the labels or on the menu.

This may seem unbelievable, yet it’s real… Companies (and even the government) use a complicated, inaccurate, and centuries-old method to calculate calorie and nutrient estimations. As a consequence, food labels may be 20-25 percent off the mark.

Even if the food labeling on the package were correct:

Reason 2: The quantity of energy in the form of calories in a meal is not always the same as the amount of energy we absorb, store, and/or utilize.

It’s important to remember that the food we consume must be digested and processed by our own bodies. The many processes involved in digestion, processing, absorption, storage, and usage, as well as our own physiological composition, all have the potential to alter the energy balance game.

So, for example:

• Because minimally processed carbs and lipids are more difficult to digest, we receive less energy from them.

• Because more processed carbs and lipids are simpler to digest, we receive more energy from them. (Think of it this way: the more “processed” a meal is, the less digestive effort it requires.)

According to studies, we absorb more fat from peanut butter than we do from whole peanuts. Nearly 38% of the fat in peanuts was expelled in the feces rather being absorbed by the body, according to the study. The fat in the peanut butter, on the other hand, seemed to be absorbed completely.

Furthermore:

We absorb relatively little calories from uncooked starchy meals (such as sweet potatoes). However, after cooking, the carbohydrates become considerably more accessible to humans, resulting in a threefold increase in calorie absorption.

Allowing starchy foods to cool before consuming them, on the other hand, reduces the amount of calories we can extract from them. (This is mostly due to resistant starch synthesis.)

Finally:

• Depending on the bacteria in our stomach, we may absorb more or less energy.

Bacteroidetes (a bacterial species) are better at extracting energy from strong plant cell walls than other bacterium species, and some individuals have more of them.

Here’s an intriguing illustration of how this process works in the workplace. USDA researchers recently encouraged test participants to eat 45 grams (approximately 12 servings) of walnuts every day for three weeks.

They discovered that individuals only absorbed 146 of the 185 calories in the almonds on average. That equates to 79 percent of the calorie value listed on the package.

A comparable study found that individuals only absorbed 80% of the calories in almonds and 95% of the calories in pistachios.

Individual variations existed in addition to the average: some individuals took more energy from the nuts, while others absorbed less (likely due to the differing populations of bacteria in their large intestines).

Finally, eating a diet rich in whole, minimally processed foods may result in you absorbing much less calories than you would anticipate. They also take more calories to digest.

In contrast, consuming a lot of highly processed meals will cause you to absorb more calories and burn less calories during digestion. (Highly processed meals are also less satisfying, have a higher energy density, and are more likely to lead to overeating.)

Because a person’s estimated calorie intake may be wrong by 25% (or more), their carefully crafted daily consumption of 1,600 calories could really be 1,200… or 2,000.

This means: As you can see, there’s a big margin of error for energy input, even if you’re a conscientious calorie counter. This doesn’t invalidate the Energy Balance Equation. It just means that if you want an accurate calculation, you probably have to live in a fancy metabolic lab.

It’s not worth the work for most people (which is one of the reasons we switched to a hand-based portion measurement approach).

The amount of ‘energy out’ varies greatly from person to person.

‘Energy out,’ or the energy expended in everyday metabolism and movement, is a dynamic, ever-changing variable.

This complicated system is made up of four main components:

1. Metabolic rate at rest (RMR)

The amount of calories you burn each day simply to breathe, think, and live is your RMR. Weight, body composition, sex, age, genetic predisposition, and perhaps (again) the bacterial population in your gut account for approximately 60% of your ‘energy out.’

In general, a larger body has a greater RMR.

Consider the following example:

• An RMR of 1583 calories per day for a 150-pound guy is possible.
• A 200-pound man’s RMR might be 1905 calories.
• A 250-pound man’s RMR might be 2164 calories.

RMR, crucially, varies by up to 15% from person to person. If you’re a 200-pound man with an RMR of 1905 calories, another 200-pound man on the treadmill next to you might burn 286 more (or less) calories each day with no more (or less) effort.

2. Food’s thermogenic impact (TEF)

Food digestion requires energy, which may surprise you. Digestion is a metabolically intensive process. (Have you ever had “meat sweats” or felt overheated after a large meal, particularly one high in protein? That’s TEF for you.)

The total energy expenditure (TEF) is the amount of calories expended when consuming, digesting, and processing food. This amounts to around 5-10% of your total ‘energy out’.

In average, you’ll spend more calories digesting and absorbing protein (20-30% of its calories) and carbohydrates (5-6%) than you would digesting and absorbing fats (3 percent).

And, as previously said, eating minimally processed whole meals burns more calories than digesting highly processed ones.

3. Engage in physical exercise (PA)

PA refers to the calories burned via activities such as walking, jogging, going to the gym, gardening, riding a bike, and so on.

Obviously, the amount of energy you spend via PA will vary depending on how often you move about on purpose.

4. Thermogenesis from non-exercise activities (NEAT)

The calories you burn by fidgeting, keeping upright, and other physical activity other than intentional exercise are referred to as NEAT. This, too, changes from one individual to the next and from one day to the next.

This means: Each of these is highly variable. Which means the ‘energy out’ side of the equation may be just as hard to pin down as the “energy in” side.

While the Energy Balance Equation may seem straightforward in theory, all of these factors make it difficult to know or manage how much energy you’re consuming, absorbing, burning, and storing.

Here’s the whole thing:

When you attempt to outwit your body, it responds by outwitting you.

The Energy Balance Equation would be complex enough even if all of the variables in the final equation were static. When you consider that changing any one of the variables affects changes in other, apparently unrelated variables, things become a little wild.

Of course, this is a good thing. When food was limited, our metabolisms developed to keep us alive and functioning. One repercussion:

When ‘energy in’ decreases, ‘energy out’ decreases as well. (When you consume fewer calories, you burn less calories.)

Not everyone has it. And not flawlessly. That is, however, how the system is intended to function. That’s how our bodies prevent hunger and undesired weight loss. It’s how humans have managed to live for the last 2 million years. The body strives to keep itself in a state of equilibrium.

Similarly, when ‘energy in’ rises, ‘energy out’ tends to rise as well. (Eating more calories causes you to burn more calories.)

To demonstrate this concept, consider how your body attempts to maintain your weight when you consume less energy and begin to lose weight*.

• Because you’re eating less, the thermal impact of food decreases.
• Because you are lighter, your resting metabolic rate decreases.
• Calories expended via physical activity are reduced when you lose weight.
• As you consume less, your non-exercise activity thermogenesis decreases.
• The number of calories that are not absorbed decreases, and you absorb more of what you consume.

*At first, this reaction seems to be very small. However, as you lose weight, the adaption process accelerates. (Or if you’re attempting to become super-lean after starting off lean.)

Check out what this looks like:  In addition to these tangible effects on the equation, reducing actual calories eaten also causes hunger signals to increase, causing us to crave (and maybe eat) more.

As a result, you’ll lose weight at a far slower pace than you would anticipate. It may even result in weight gain in certain instances.

To make matters worse, a surge in cortisol caused by dietary stress may lead our bodies to retain more water, making us seem “softer” and “less lean” than we are.

Interestingly, this is only one example of the incredible and resilient reaction to manipulating a single variable (in this case, actual calories eaten). When attempting to modify the other variables in the equation, the results are identical.

According to studies, increasing physical activity beyond a particular threshold (e.g., by exercising more) may cause:

• Increased desire and consumption of more calories
• As we absorb more of what we consume, we absorb less calories.
• RMR has dropped.
• NEAT has decreased.

In this case, here’s what the equation would look like: In the end, these are just two of the many examples we could share. The point is that metabolism is much more complicated (and interdependent) than most people realize.

As a consequence, depending on calorie counting or attempting “what used to work” for you won’t always bring you the results you desire. Your weight-loss or weight-maintenance methods must change as your energy balance changes.

Understanding energy balance allows you to have more realistic expectations about how your body will evolve.

It’s essential to remember that many of these adaptations (e.g., reduced RMR, PA, NEAT, etc.) take time to develop if you have a lot of body fat to shed. This “adaptive thermogenesis” kicks in when you lose weight.

It’s also essential to understand that your metabolism will respond differently to changes in energy balance depending on your genetics.

Your age, genetic composition, biological sex, whether you’ve had comparatively more or less body fat and for how long, medicines you’re taking, and the makeup of your microbiome will all influence how much you can lose or gain. and most likely a slew of other variables we’re unaware of.

However, let us attempt to imagine how this could function.

Scientists at the National Institutes of Health analyzed data from individuals who had lost weight and developed a mathematical model that depicts how weight and fat reduction occurs in real life.

Using the Weight Loss Calculator, we may experiment with it.

Let’s start with a 40-year-old man who weighs 235 pounds and stands 5’10” tall. We’ll refer to him as Frank.

Frank has a desk job and is only somewhat active in his spare time. According to this, he need 2,976 calories a day to maintain his present weight.

His daily calorie intake is reduced by 500 calories to 2,476 calories. And he has no intention of altering his physical activities.

You’ve undoubtedly heard that a pound equals 3,500 calories, which implies that if we take away 500 calories from Frank every day, he’ll lose a pound each week (500 x 7 days = 3500 calories).

He should end up at 183 lb after one year of consistently eating 500 fewer calories every day. (According to this math, then, he would weigh 0 lb within 5 years, which should raise some red flags.)

However, we all know that this isn’t how it works in real life.

Frank weighs himself at the end of the year. He weighs 205 pounds.

What the heck is going on here?

That’s 22 pounds above my ideal weight!

Frank screams angrily at his wife Maria, who knowingly grins. She, too, is 40 and has struggled to shed weight since having two children in her mid-thirties.

She says, “Tell me about it.” Even though I’ve been exercising and eating quite healthily, I’ve consistently lost and gained the same 10 pounds.

Then they both think to themselves:

After all, I may as well try that juice detox. My body is clearly damaged.

No, no one is harmed. Don’t go on a juice fast just yet.

Frank and Maria, on the other hand, might both benefit from a better knowledge of how weight reduction works. They may then establish suitable behavior objectives for themselves and have reasonable expectations for their development.

(Frank and Maria opt out of the juice fast and enroll in Coaching instead.) Maria “only” dropped 7 pounds over the course of a year, but she developed 5 pounds of muscle [which implies she shed 12 pounds of fat]. Her toned arms and beautiful skin make the other mothers envious. Frank has slimmed down to 185 pounds and is attempting to persuade Maria to purchase him a mountain bike.)

Is it true that dieting harms the metabolism?

Regardless of what you’ve heard,

No, reducing weight does not cause your metabolism to malfunction.

However, because of the adjustments your body makes in reaction to fat loss (and, in fact, to prevent fat loss), individuals who have lost a substantial amount of weight will always have lower ‘energy out’ than those who have always been lean.

Rather:

Adaptive metabolic, neuroendocrine, autonomic, and other changes occur as a result of losing weight and keeping it off.

We spend less energy as a result of these changes, around 5-10% less (or up to 15% less at severe levels) than would be expected based on our weight.

Unfortunately, due of this adaptive response, dieting requires 5-15 percent less calories per day to maintain the same weight and level of physical activity as someone who has always been that weight.

(Or even less, potentially, because as we learned in the very beginning, the RMR of people of the exact same age/weight/etc. can still vary by up to another 15 percent.)

This implies that someone who has never been overweight may only need 2,500 calories to maintain their weight, while someone who has had to diet to get that weight may only require 2,125-2,375 calories to maintain their weight.

We don’t know how long this reduced energy use will continue. It has been demonstrated in studies that it may linger for up to 7 years following weight reduction (or longer; 7 years is the longest time it has been examined). This indicates that it is either permanent or chronic.

This is especially true for individuals who have tried and failed to lose weight in the past, or for fitness competitors who may alternate between being very thin and being overweight during the off-season.

Adaptive thermogenesis seems to respond more strongly or more quickly with each consecutive yo-yo of severe body fat changes, but I don’t have evidence to back this up (to my knowledge, no one has researched it).

All of this helps to explain why some individuals believe that dieting has “damaged” their metabolism. (As well as why some scientists believe “metabolic damage” exists.)

However, nothing has been really “harmed.”

Instead, their bodies have just grown more responsive to different hormones and neurotransmitters in a predictable way. Their metabolic rates are lower than anticipated by different laboratory formulae, which is understandable.

So, where do we go from here?

These objectives may be achieved even by those whose bodies oppose fat reduction or muscle development.

For various individuals, all physiological changes, such as weight loss or growth, fat loss or increase, and muscle loss or gain, require varying levels of work and time.

Even if your body resists weight reduction, you may still shed fat, build muscle, and alter your physique drastically.

Our Coaching Halls of Fame for men’s and women’s Finalists are proof of that.

What to do next: Here are some suggestions from.

Although the physiology of weight reduction is complex, the greatest methods for losing weight and keeping it off aren’t.

1. Consume a lot of protein.

Protein is necessary while attempting to lose weight or fat for a variety of reasons.

• Protein aids in the maintenance of lean body mass (which includes connective tissues, organs, and bone as well as muscle).

• Protein boosts satiety, which means you’ll feel fuller even if you eat less. (In addition, consuming more protein tends to make individuals eat less overall.)

• Because of the enhanced thermic impact of food, just consuming more protein burns more calories.

For example, if you consume 2,500 calories per day, 15 percent of which comes from protein, 50 percent from carbohydrates, and 35 percent from fats (about typical for US people), digestion burns around 185 calories each day.

If you keep your total calorie intake the same but raise protein to 30%, carbohydrates to 40%, and fat to 30%, your TEF will be about 265 calories per day.

• 6-8 palm-sized servings of protein per day for highly active males

• 4-6 palm-sized servings per day for most active ladies.

Check out our Calorie Control Approach infographic for a full guide on using your hand to measure meals.

2. Consume a diverse range of fruits, vegetables, high-quality carbohydrates, and healthy fats.

Vegetables are high in vitamins, minerals, phytonutrients, water, and fiber, which may help you remain full between meals, stay healthy, and recover from exercises.

• For most active guys, we suggest 6-8 fist-sized doses each day.

• Most active women should have 4-6 fist-sized portions each day.

Carbs will fuel your workouts, increase leptin (an essential hormone), keep your sex hormones in check, and keep you from feeling deprived.

Fats also regulate sex hormones, strengthen the immune system, reduce inflammation, and enhance the flavor of food.

• This equates to 6-8 handfuls of high-quality carbohydrates and 6-8 thumbs of healthy fats each day for most active guys.

• 4-6 handfuls of high-quality carbohydrates and 4-6 thumbs of healthy fats every day for most active women.

Check out our Calorie Control Approach infographic for a full guide on using your hand to measure meals.

3. Increase or decrease your intake when you reach or avoid a plateau.

As you lose weight, you’ll need to reduce your calorie intake even more to maintain your success, since your smaller body burns less calories and your body adjusts to your diet.

Remove 1-2 handfuls of carbohydrates and/or 1-2 thumbs of fats from your daily diet and be ready, willing, and able to modify portion sizes. Then evaluate and make any necessary adjustments.

However, according to one research, weight reduction plateaus are caused by “an occasional lack of diet adherence” rather than metabolic adaptations. In other words, not adhering to a dietary plan on a regular basis.

According to research, we typically believe we are eating less and exercising more than we really are. So, before you assume your body is impeding your efforts, take an impartial look at your real energy in and out.

4. Recognize that this is a difficult situation.

So many factors affect what we eat, why we consume it, and when we eat it.

Eating and body size / fatness are often attributed to a lack of information, willpower/discipline, or laziness. In reality, a variety of physiological, biochemical, psychological, social, economic, and lifestyle factors, as well as individual knowledge and beliefs, affect food consumption and body composition.

Creating an atmosphere that promotes healthy food choices and discourages bad ones is one of the easiest ways to make your decision-making processes simpler. This may imply altering your daily schedule, who you spend time with, where you spend time, and what food you have on hand.

However, keep in mind that weight reduction may and should be gradual; try to drop 0.5-1 percent of your body weight each week.

This helps to maintain muscle mass while reducing the adaptive metabolic responses to calorie restriction and weight loss. More muscle loss without additional fat loss, as well as a greater adaptive response, is associated with faster weight reduction.

5. Alter your calorie and carbohydrate intake.

If you want to become very slim, you can’t simply depend on linear diets to get you there. You may help to restrict how much the metabolism-regulating hormone leptin lowers (or briefly raise it back up) by carefully cycling calories and carbohydrates, reducing the adaptation and hunger response.

*Note: This is a higher-level approach for fitness competitions and top athletes who need to become very thin (i.e., a body fat percentage of 6-9 percent for males and 16-19 percent for women). It’s not something that the ordinary person would be interested in.

6. Refeed on a regular basis.

Even planned calorie and carb cycling may not be adequate to reach extreme levels of leanness. So bring out the heavy guns and use some re-feeds to temporarily increase leptin and insulin levels and maintain fat reduction.

**Note: This is a higher-level strategy for fitness competitors and elite athletes who need to get very lean (i.e. <6 percent body fat for men, and <16 percent for women).

7. Include resistance, cardiovascular, and recuperation activities in your workout.

Resistance exercise aids in the preservation of essential muscle mass, the burning of calories, and the improvement of glucose tolerance. Cardiovascular exercise enhances the health of your cardiovascular system, aids in energy expenditure, and may help you recover faster.

But don’t go overboard with either.

Recovery activity (such as foam rolling, walking, and yoga) aids in the consistency and intensity of resistance and aerobic training, making it more effective. It also aids in stress reduction (cortisol reduction), which aids in body fat loss and maintenance.

Aim for 3-5 hours of intentional exercise each week.

8. Look for methods to boost NEAT.

Small improvements in exercise may add up to hundreds of calories each day, making a significant impact in fat reduction efforts.

Here are some suggestions: Get a stand-up or treadmill desk; fidget; pace while talking on the phone; climb the stairs; park your vehicle farther away from your destination.

9. Establish a consistent nighttime sleep pattern and learn to control your stress.

Sleep is just as crucial to your success as diet and physical exercise. Don’t fool yourself into thinking you can get by with less. It’s just untrue.

When individuals reduce their stress levels, they often shed a lot of bodily water. Then they realize that they may have lost weight as well. (Plus, they may find that chronic inflammation decreases, which is a plus.)

Mental and emotional stress are included in this category. According to research on cognitive dietary restriction (i.e., worrying and stressing out over food), continuously and adversely fixating on what you eat (or don’t) may have the same negative impact as dieting rigidly.

However, we need some stress in order to develop and grow, so locate your stress sweet spot.

Self-compassion is a good thing to have.

There will be meals or days when you don’t eat as much as you “should.” It’s all right. It can happen to anybody. Recognize, accept, and forgive yourself before getting back on track.

Self-compassion and flexible eating are linked to a lower BMI and a healthy body weight, as well as reduced self-reported calorie intake, less anxiety and stress, and a better connection with food, according to research.

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Diets that restrict calories or the total amount of food consumed can lead to weight loss. However, in some cases, these diets can actually harm your metabolism. That’s right, you might be able to lose weight by eating very little, but it’s not always good for your body.. Read more about metabolic damage weight gain and let us know what you think.

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