While you may not realize it, there are a few simple tricks to thinking that eating less will lead to weight loss. Most of us are familiar with the calorie balance concept, which holds that if you consume fewer calories than you burn, then you will lose weight. However, this is not the only way to think about weight loss. If you eat fewer calories than you burn, you will lose weight, but you can also eat more, but still lose weight, or gain weight. It’s a common misconception that you can’t gain weight on a calorie deficit.
One of the biggest fears many people have about weight loss revolves around eating too little, which can actually lead to weight gain.
You’re paying attention to your diet and your workouts, but you’re not seeing results. Has your metabolism slowed down? Are your hormones out of whack? Is it really possible to gain weight by not eating enough? Here’s what’s really going on – and how you can fix the problem.
How can I eat so little and still gain weight?
Have you ever felt that way? (Or do you have a client who does?).
In the years that I have been coaching, this question keeps coming up, both from clients and from other coaches.
You’re confused. Disappointed. Maybe even angry. (Or hungry, of course).
Even if they do everything they can, including eating less – probably a lot less – they still don’t lose weight. In fact, they can even grow.
Do a quick search on the internet and you will certainly find many explanations.
Some say the laws of energy balance apply and people don’t count calories correctly. Others talk about a starvation diet or a strange metabolic or hormonal problem.
So what is it? Is there a problem with them? Are their bodies broken? Is it in their heads?
Or can you really gain weight by not eating enough?
We’ll find out.
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Truth: Thermodynamics does not lie.
You’ve probably heard this expression before: the laws of thermodynamics. Or maybe you’ve heard of energy balance. Or : Calories in, calories out.
Let’s see what this really means.
Thermodynamics describes the way energy is used and changed. It’s simple: We get our energy in the form of food and consume it through activities such as. :
- basic metabolic functions (respiration, circulation, etc.)
- Physical activity (daily activities, targeted exercise, etc.)
- Heat production (also called thermogenesis)
- digestion and excretion
And the truth is…
Energy balance (calorie intake, calorie expenditure) determines body weight.
- If we take in more energy than we use, we gain weight.
- If we take in less energy than we use, we lose weight.
This has been repeatedly tested by researchers in many contexts.
That’s as close to a scientific fact as you can get.
Of course, many factors affect both sides of this seemingly simple equation, which can lead to confusion:
But humans do not violate the laws of thermodynamics.
But what about unexplained weight changes? When was the last time you ate extensively and woke up lighter? If you feel like you’re doing everything right, but you can’t lose weight?
No, even though it may seem like we are challenging energy against energy outwardly, this is not the case.
What about the doctor who says insulin resistance (or some other hormone) breaks the equation?
Hormones can affect the ratio of lean mass to fat you gain or lose, but they don’t cancel out the energy balance equation.
But as the title of the article suggests, it’s easy to see why people – even internet gurus and doctors – get confused about this topic.
One of the reasons why…
Measuring your metabolism is not an easy task.
The problem is that your exact metabolic needs and reactions are not easily measured.
You can estimate your basal metabolism, which is the amount of energy you need to stay alive. But the measurements are only as good as the instruments we use.
The best instruments for measuring metabolism are closed metabolic chambers, but few of us spend time in them on a regular basis.
This means that while we can estimate our metabolism at the gym or with fitness trackers, just as we do by counting calories on labels, these estimates can be wrong by 20-30% in normal, young, healthy people. In other populations they probably differ even more.
Of course, if we could measure exactly how much energy you consume each day, and then measure exactly how much energy you take in, we could determine if you are really eating too little for your body’s needs.
But even if we could figure it out outside the lab, which we can’t, it wouldn’t help. Since energy production is dynamic, i.e. each variable changes when another variable changes (see below).
In other words: Until we can accurately measure how much energy you take in and produce from minute to minute, we can’t know exactly how your metabolism works and how well it adapts to the food you eat.
So we have to guess most of the time. And our assumptions are wrong.
Not only that, but the concept of not eating enough is subjective.
Think about it. When you say you don’t eat enough, you mean …..
- Are you eating less than usual?
- Are you eating less than you were told?
- Are you eating less than you should?
- Are you eating less than you need to be healthy?
- Are you eating less than your estimated metabolic rate?
- Are you eating less than your actual metabolic rate?
And how often does this happen? You, uh…
- Do you eat too little at a meal?
- Do you eat too little in the day?
- Do you eat too little every day?
- Do you eat too little most days, but too much some days?
Without clarity on some of these issues, you can see how easy it is to assume that you are eating too little, but not less than your actual energy expenditure, even if you have taken a metabolic test and it shows that you are eating less than that figure.
In most cases, the problem is one of perception.
As humans, we don’t know how to properly estimate the amount of food we eat and consume. We think we eat less and burn more than we actually do – sometimes as much as 50%.
(Interestingly, lightweight people trying to gain weight often have the opposite problem: they overestimate their food intake and underestimate their spending.)
It’s not that we lie (although we can sometimes deceive ourselves and others about our consumption). Most importantly, we have trouble estimating portions and calories.
This is especially difficult now that plates and portions are bigger than ever. And high-energy, incredibly delicious and brain-friendly food is ubiquitous, cheap and socially encouraged.
When people start carefully monitoring their portion sizes with their hands or with scales and measuring cups, they often find out to their horror that they are eating much more than they intended.
(My client once discovered that he had used ten tablespoons of olive oil to fry fries, or 1200 calories, and not two tablespoons, or 240 calories, as he thought. Oops.)
At other times, we can do everything right at most meals, but the energy can slip away from us if we don’t notice.
Here’s a great story that illustrates this.
A few years ago, Dr. Berardi (JB, as he is called here) went out to dinner at a famous restaurant with some friends. He ordered one of their healthy meals with an emphasis on protein, vegetables and pure carbs. Then he finished his dinner with a cheesecake.
Curious to see how much energy he had used, he checked.
5. 1.000. Calories.
Unbelievably, he didn’t feel so full after that.
If the calorie content of a meal surprises someone with JB’s knowledge and experience, what would most normal eaters do? Good luck trying to get an eye for an eye.
Also, imagine a scenario where you were malnourished at almost every meal for a week and had a negative energy balance of about -3,500 calories. Then you’ve included 5,000 calories in one meal, a healthy menu plus dessert.
This meal alone results in a theoretically positive energy balance for the week (+1,500 calories) and thus weight gain!
Seriously, though: How would you feel if you gained weight after 20 perfect meals in a row and one not so good one? You will probably feel that your metabolism is disturbed.
You probably think you can gain weight if you don’t eat enough.
But even here the laws of thermodynamics are not violated. Instead, a lot of calories have crept into your body without you even realizing it.
Furthermore, the dynamic nature of metabolism can be confusing.
Another reason it’s easy to think you’ve gained weight because you haven’t eaten enough (or at least haven’t lost weight while eating less) is that your metabolism doesn’t work like a computer.
For example, you may have heard that a pound of fat is worth 3,500 calories. For example, if you reduce your calories by 500 per day, you will lose one pound per week (7 x 500 = 3,500).
(Unless, by the end of the week, you are eating 5000 calories in one meal, in which case you will gain weight).
But that’s not how the human metabolism works. The human body is a complex and dynamic system that responds rapidly to changes in the environment.
When you are malnourished, especially over a long period of time (this part is very important), this complex system adapts.
Here is an example of how this can be done:
- You use less energy to digest your food because you eat less.
- Your resting metabolism drops because you weigh less.
- The calories burned by physical activity decrease because you weigh less.
- Thermogenesis unrelated to physical activity (daily arousal, exercise) decreases and you consume less energy throughout the day.
- Your digestion slows down and you absorb more energy from your food.
Your body will also adjust feedback loops and hormonal signals. For example:
- Appetite and hunger hormones increase (i.e. we feel more like eating, are more stimulated by food signals, may feel more desire).
- Satiety hormones decrease (meaning it’s harder for us to feel full or satisfied).
- Thyroid hormones and sex hormones (both involved in metabolism) decrease.
Your planned daily deficit of 500 calories can quickly turn into 400, 300, or even 200 calories (or less), even if you intentionally exercise as much as before.
Talk about movement: The body has similar mechanisms when we try to overcome overconsumption.
For example, research shows that increasing physical activity above a certain threshold (more intense exercise) can lead to :
- Increased appetite and number of calories actually consumed.
- Increased energy absorption
- Reduced resting or basal metabolic rate
- Less fidgeting and spontaneous movement (aka NEAT).
In this case, the equation would look like this:
These are just two of the many examples we could give.
There are other factors, such as the health of our gastrointestinal microbiota, our thoughts and feelings about eating less (i.e. whether we perceive eating less as stressful), etc.
The fact is that metabolism is much more complex (and interdependent) than many people think.
All of this means that if you eat less, you may not lose as much weight as expected. Depending on how much you eat and how long you starve yourself, these physiological and behavioral factors can actually cause you to gain weight again in the long run.
People are also incredibly diverse.
This also applies to our metabolism.
While the average responses described above are correct, our unique responses, genetics, physiology, etc. mean that our calorie needs will differ from those of other people or from those predicted by laboratory equipment (and the equations on which it is based).
Imagine two people of the same gender, age, height, weight and lean mass. According to the calculations, they should have exactly the same energy intake and thus the same energy requirement.
We know that’s not the case.
- Your basal metabolism – remember, this is the energy you need to fuel your organs and biological functions to stay alive – can vary by as much as 15%. For the average woman or man, that’s about 200 to 270 calories.
- Genetic differences also play a role. A change in just one FTO gene can make a difference of 160 extra calories.
- Sleep deprivation can lead to a 5-20% change in metabolism, which equates to 200-500 extra calories.
- In women, the menstrual cycle phase can affect metabolism by about 150 extra calories.
Even the same person’s metabolism can easily vary by 100 calories from one day to the next or even throughout the day (depending on the circadian rhythm of waking and sleeping, for example).
These differences can grow quickly, and this list is not even complete.
If you really want to dig into the factors that affect our energy levels, read this article:
The multifactorial nature of body weight.
In summary, I hope you understand why the equations used to predict the calorie needs of the average person may not be correct for you. So if your calorie intake is lower than your measured (estimated) consumption, you may gain (or not lose) weight.
Therefore, some experts, unaware of the limitations of metabolic measurements, try to find all sorts of complex hormonal or environmental causes for what they believe is a violation of thermodynamics.
However, the answer is much simpler.
It’s just that the numbers weren’t very good.
And yes, water retention is a thing.
Cortisol is one of our stress hormones that affects the fluid balance in the body.
Restricting food and nutrients is stressful (especially when you think about it). When we are stressed, cortisol tends to rise. People are talking about being more stressed than ever these days, so it’s easy to make it a serious stress.
When cortisol increases, our bodies can store more water, making us feel softer and less thin than we really are. This water retention can mask fat loss and give the impression that you are not losing fat and weight, when in fact you are.
Here’s an example.
A good friend of mine (and former high school hockey teammate) fought his way into the NHL. He played several seasons in the AHL (a level below the NHL) and was just called up to the pro team.
The NHL club wanted him to stay under 100kg, which wasn’t easy for the 180cm man. He discovered that a low-carb diet allowed him to maintain his weight of 218 pounds.
However, her nutritionist told her that it was okay to have high-carb days once in a while.
Unfortunately, he had one of those high-carb days – he went to eat sushi with his teammates – right before his first NHL practice.
When he reported to the NHL team the next day, he was called to the general manager’s office for weigh-in. He weighed 105 kilos.
Thank you, carbs and salt!
My friend was devastated. To make matters worse, two days later his weight had increased to 218 pounds.
Okay, but what if I am careful with my income and expenses?
You might nod when you realize how complex your metabolism is. How calorie counting can be inaccurate. How changeable we all are. How hard the body tries to maintain the status quo. And how poorly we can estimate our own income and expenses.
But what if you pay attention to your diet? Do you keep a food diary? Are you counting steps? Even visit a local research lab to measure your metabolism? And it still doesn’t fit?
Well, that brings us back to what we’ve been talking about so far:
- The number of calories in the food you record may be higher than expected, due to mislabeling or minor errors in your own measurements.
- Your energy needs may be lower than estimated (or even measured). It might have something to do with the fact that…
- You consume less energy during exercise than your fitness tracker or exercise device would suggest.
- You have less dry matter than you think, or it doesn’t use as much energy as you think.
- You absorb more energy during digestion than you think (for example, if your gastrointestinal passage is slow or if your microbiota is very good at extracting nutrients).
You may just be missing data.
As mentioned above, you’re probably not lying, but you might also forget to bring a few pieces of your kids’ chicken nuggets that you didn’t want to throw away. Or an extra spoonful of peanut butter. Or a large glass of wine that you counted as a medium. Also, the calorie information on food labels can (and often is) incorrect.
You may feel like your workout is high intensity, even though you spend most of your time on the bench between strength sets with low reps. Maybe you were so hungry after your workout that you ate more than you intended (but you thought it would all go to muscle building, so it didn’t matter).
It happens, we’re all human.
Careful measurement and monitoring of energy consumption may be useful.
When we measure and track our food intake, we better understand what we are eating, have a more realistic idea of portion sizes, and help ourselves to be consistent and responsible.
But measuring and controlling is certainly not an ideal strategy.
It can be stressful and time consuming. Most people don’t want to do this forever.
And it can distort the exact number of calories consumed and burned, making us think we are eating less than we are burning, even though that is not the case.
What about legitimate medical problems?
When we get to this point in the conversation, people usually ask if there are any underlying health problems or medications that may be affecting their metabolism, weight and/or appetite.
The answer is yes.
These include polycystic ovarian syndrome (PCOS), certain medications (corticosteroids or contraceptives), severe thyroid disorders, altered sex hormone production, leptin resistance, etc.
However, this happens less often than most people think, and even if you have a health problem, your body is not violating the laws of thermodynamics.
It’s just that, as mentioned above, your calorie intake is lower than expected. And a few extra calories can sneak into your body as you eat.
The good news is that weight loss is still possible (albeit at a slower pace).
If you believe that you are correctly assessing your food intake, regularly exercising at least 5-7 hours per week, controlling your sleep and stress, getting qualified nutritional help, and absolutely following all the basic rules, it may be time to consider further discussions and testing with your doctor.
So what can you do?
If you feel like you’re eating less than you need (in other words, you seem to be eating too little) but you’re still not losing weight, try the following steps.
Measurement of consumption
Use the tool you prefer. Your hands, scales and spoons, photos, food diaries, etc. It doesn’t matter.
Follow your diet for a few days or an entire week to see if it matches what you thought you were eating. We often wonder.
Sometimes just keeping track makes us more aware of the products we consume, which helps us make better decisions.
Be kind to yourself.
It may seem that being strict or critical is a good approach, but it’s not. This only adds to the stress.
On the contrary, research shows that being kind and gentle with yourself (with mature honesty about your choices) leads to a healthier physique, better food choices, better fitness goals, less anxiety and stress, and an overall better relationship with food.
There will be meals or days when you don’t eat like you should. It’s all right, it’s all right. It happens to everyone. Acknowledge it, accept it, forgive yourself and get back to work.
Choose mostly whole foods that are less processed.
Foods that do not cause hypervigorance or hypertrophy are harder to digest. They do not cause hypothalamic inflammation or leptin resistance.
They are rich in nutrients (vitamins, minerals, water, fiber, phytonutrients, disease-fighting chemicals, etc.) and generally contain fewer calories.
And they are much better at keeping you full and satiated.
Choose whole foods that you like and will eat again and again.
Play with the amount of macronutrients.
Some people respond better by eating more carbs and less fat. Others respond better to a low-fat, low-carbohydrate diet.
There is no one optimal diet for everyone. We all have different preferences and even different reactions to foods and macronutrients. So play around with it a bit and find what works for you.
Make your own decisions.
Be guided by your adult values and core principles when you eat. Choose foods in awareness of the results you expect.
Avoid mind games like If I’m good, I might be bad or If I pretend I didn’t eat a cookie, it didn’t happen.
Look at your behavior with open, mature and wise eyes.
Accept that every choice has consequences.
And enjoy spoiling yourself once in a while.
If you continue to have difficulty, contact your trainer.
It is very difficult to change someone’s behavior and lose weight permanently. Especially if you’re trying to do it alone.
Talk to a qualified and compassionate coach or specialist who can help you through this difficult situation.
(Can I offer support?)
If you are a coach or professional, you can help people do this here.
When working with clients or patients as a caregiver, show compassion. Remember, it’s incredibly easy to think you’re doing everything right and still not see results.
Instead of jumping to conclusions or starting to explain why your client is not successful, follow these steps:
Step 1: Be compassionate and curious.
Understand that most people in this room are probably angry and/or blaming themselves. Don’t be so hard on them and call them liars.
Be empathetic and curious.
Step 2: Collecting (accurate) data.
Let people show what they do to the best of their ability. Photos, food diaries, tracking apps…. whatever suits their level of preparation, readiness and ability.
While careful monitoring is usually not a good long-term solution, it can both help you get more accurate data.
Step 3: Have a crucial conversation.
If you think that means you’re a hardcore coach, you’re wrong. Remember:
- They work in alliance against the problem, not against each other.
- You both want your client or patient to succeed.
State facts, not opinions. What you see and what they see is probably different.
Step 4: Help them feel safe.
If someone is hiding food from you, it’s at least partly your responsibility.
For some reason, the person is uncomfortable telling you that they are not doing what they think they should be doing.
This issue needs to be studied together. Take it easy. Be careful. With a curious and open mind.
Last note of body composition.
Before I close, I want to say something important.
In this article, I have chosen to focus only on the effect of body weight on the energy balance equation, because that is the only thing that truly describes the equation (i.e., pure energy transfer).
Changes in body composition (i.e., the relative ratio of lean tissue to fat in the body) are, if you can believe it, much more complex and much less well understood.
If you are a trainer or want to become one….
Learning how to educate clients, patients, friends or family members about healthy eating and lifestyle changes that fit their bodies, preferences and circumstances is both an art and a science.
If you want to learn more about both, consider Level 1 certification.
Frequently Asked Questions
Why am I gaining weight when I barely eat?
You may be eating too much.
Can eating too little lead to weight gain?
Yes, eating too little can lead to weight gain.
Why do I put on weight so easily?
You may put on weight easily because you have a slow metabolism.
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