What Do You Eat for Weight Loss?

[Salathor]

Eat only whole foods. Buy no grain that is less than 10% fiber (I personally make an exception for short grain brown rice, which is about 9% fiber). Buy nothing that comes in a container unless it has 3 or fewer ingredients, all of which you can name. Eat lots of whole grains and vegetables, a little fruit, and a little meat/dairy. Enjoy extra virgin olive oil and vinegars for flavor.

Heavily limit sugar, regardless of where it comes from (this means fruit, too!).

This is also a cheap and planet-friendly way to eat. Almost like it's meant to be.

That's my thing, anyway.

[banker22]

@slowtraveller how are you doing? Did you manage to get back to the 2x24h fasts per week and install it as a habit?

[Violets]

Just gonna add a +1 to intermittent fasting...I found it very helpful and picked the idea up here as a lurker. I was never religious about it, if I got really hungry I'd eat even if it was outside my eating window. I lost about 50 pounds I picked up when I was depressed and drinking a lot. I never read the literature, just random people on here mentioning it....tried it, it worked.. lost the weight over the course of a year or so, more or less still do it cause it's comfortable.

[philipreal]

I'm just finishing up a weight loss competition at work where I've lost about 15 pounds in 10 weeks*, and I don't feel like I tried very hard in order to do that. I went with the warrior diet where you eat one meal a day and didn't eat much outside that time, generally just free fruit available at work. My guide was if I felt hungry every so often I was probably losing weight at a reasonable rate. If you just don't allow yourself the opportunity to eat very much by not having tempting snacks around and only wanting/being able to eat so much in one meal, losing weight may just happen. At least it did for me.

*The actual number for competition purposes will probably be in the 20 to 25 lb range, but that's because I did some things like drink a half-gallon of water shortly before the first weigh in. I'm here estimating the actual weight change that can last if I choose for it to.

[conwy]

For general health including fat loss, it seems the Mediterranean Diet has come out as a consistent winner over many studies. Walter Willett's book Eat, Drink and Be Healthy seems to give the most rigorous account of the scientific theory and evidence supporting this. This book is practically encyclopaedic, covering many high-quality studies, but focussing especially on broad populations over long time periods, such as the Nurses Health Study.

So far (touch wood) I've been achieving steady and consistent abdominal fat loss using my own idiosyncratic version of the Mediterranean Diet, combined with fasting and exercise (body weight strength training and brisk walking).

My diet over the last few months has basically looked like this:

Morning to early afternoon:

• Plain black coffee, several cups. Otherwise, fasting.

Late afternoon lunch:

• Small plain low-fat yogurt, around 150g
• 2-3 cups frozen berries, around 120g
• Topped with decaf instant coffee, a delightful 0-calorie flavour boost!

• Small tin of salmon in water, 100g
• Small can of edamame beans in water, 125g
• Half cup yeast flakes, around 16g
• Topped with hot sauce - ingredients just vinegar, peppers and salt, close to zero calories

This is intentionally high protein, as I have it around my workout time.

Big multi-course evening dinner (culinary event of the day!):

Course one:

• Small tin of sardines, 125g, quickly fried with thyme, peppercorns, lime, etc.
• Avocado, quarter, mashed and topped with garlic and lime juice
• Sweet tomato sauce, made by gently frying onions, tomato paste, balsamic vinegar and chilli powder, maybe adding some sage or mint
• Beans - rotating between chickpeas topped with cumin powder, kidney beans with rosemary, black beans with oregano or lentils with tamari sauce for a meaty "umami" flavour

The beans are especially fun to play around with! I like to experiment with various herbs and spices. For example I've recently been cooking a Cuban-style variation - black beans with cocoa powder and hot scotch bonnet peppers and swapping the sauce for a side of fried plantains and the sardines for some fried tuna and vinegar to mimic "pulled pork".

Course two:

• Steamed vegetables, typically a big pot full of colourful plants - steamed broccoli, cauliflower, red cabbage, carrot, etc
• Topped with 1 tbsp balsamic vinegar, 1 tbsp olive oil, herbs, chilli powder.
• And a side of yeast flakes or fried tofu

Dessert:

• Steel cut oats, half a cup, mixed with cocoa powder, soaked for 30 min, then microwaved for 3 minutes
• Topped with half a cup of nuts, 4 dates, 1 teaspoon seeds, dash of cinnamon powder

Small supper if I'm still feeling peckish:

• Small tin of edamame beans
• Fermented food - Sauerkraut or Natto

Some considerations:

• Enjoyment - Should taste good and be satisfying for you to keep it up over the long-term. I'm not a fan of harsh, difficult diets.
• Sustainability - Should be environmentally friendly and low carbon footprint. Long-term I do want to reduce the fish and dairy content as I find suitable substitutes. I might consider B12, calcium and protein supplementation.
• Cost - Should be fairly low cost. Some of these ingredients can be swapped for cheaper alternatives when budget is tight. E.g. normal oats are much cheaper than steel cut.
• Healthy - High in fibre, anti-oxidants, vitamins/minerals, protein, good fat. Low in salt, sugar and bad fat.
• Portion control - I keep track of calories in a spreadsheet. I always use convenient utensils to measure things out - one small quarter-cup, one half-tablespoon and one teaspoon. By making a habit of measuring the food out, I can avoid eating too much or too little.
• Mindfulness - I try to focus on the food, appreciate it and enjoy it with gratitude. For this I've been most inspired by the book How to Eat by Thich Naht Hanh.

With this diet I've achieved significant loss of abdominal fat while preserving my muscular strength. I don't feel hungry often and have been able to sustain a pretty good steady level of energy throughout the day.

Recent photo:

[Lemur]

That's a solid diet @conwy.
Reminds me ... definitely need to get more fatty fish in my diet. I eat salmon occassionally. I also don't eat edamame at all. Need to explore that one.

Not sure if I have posted in this thread but to answer the question "what do you eat for weight loss." it is pretty easy for me because I'm pretty robotic in my method and in 5 easy step I think covers 95% of the progress you need...the other 5% is squabbling over details and has diminishing returns:

1. Find TDEE and subtract 500. Track calories. Adjust as weight decreases. Be consistent.
2. Consume at least 150 grams of protein from mostly lean meats and lentils/beans. (this is based on my needs but a commonly held formula is to calculate 1.6-2.0 grams of protein per kg of bodyweight).
3. Consume 25-50 grams of fiber from veggies and seeds.
4. Steps 2 & 3 from mostly whole foods but can squeeze in some junk* for flexibility.
5. Perform resistance training + low intensity cardio to maintain muscle mass. Walking a lot also adds up calories burned.

* Regarding letting yourself consume some junk on a diet - does look like a weird recommendation but there is a phenomenon where being overly rigid in your eating patterns and food can lead to binging and even eating disorders in the worst case. For most people, it is best to allow a little bit of flexibility. As they say dieting is a marathon and not a sprint. I understand how debatable this is (like telling an alcoholic they can consume modestly) so do take your own personality into consideration and I would not want to apply this advice for all.

One more add and its slightly off-topic about food, but from the various books and articles I've read over the years, I think getting your emotional affairs in order and mentality for a diet is pretty crucial. Eating protein, whole foods, fiber, etc. are all things that can help with satiety but at the end of the day, if you're on a diet, you will be hungry. Each day is a battle between system 1 vs system 2 thinking. Accepting hunger as part of the process is crucial.

[delay]

Accepting hunger as part of the process is crucial.

Thanks for sharing your experience. My experience is the opposite: I cannot sustain hunger for more than a few months in a row.

Intermittent fasting (= eating window from 1400 to 2000) works for me. Combined with whole foods at least a few days a week. I never feel hungry. Healthy weight for two years now.

[philipreal]

I think both experiences don't have to conflict. Feeling somewhat hungry while in the process of losing weight is a pretty good heuristic that you are making progress on the weight loss front, and it was one I held to recently while dropping 15 pounds in 10 weeks at a very comfortable rate. In that sense, welcoming the feeling of hunger as a fairly necessary and beneficial part of that process was good for me. However, you shouldn't be trying to consistently lose weight for many months in a row, from what I know bodies respond negatively to that, it's better to break it up with a few weeks of maintenance eating every now and then. Once you have lost weight and are maintaining a healthy weight you shouldn't need to be regularly feeling hungry as part of it, although of course everyone is different.

[Lemur]

Right - I'm specifically talking about a caloric deficit. Hunger is very very common and something that has to be dealt with. As far as intermittent fasting is concerned, does not work for everyone. I even had a MMG about that topic a few years ago - I myself could not sustain it and was better off without it. I ended up just thinking about food all day so I prefer the old-school style of 3 square meals a day when dieting. It gives me something to look forward to in increments. Most of the time maintaining a healthy weight shouldn't cause hunger unless you lost a substantial amount of weight and you're trying to maintain below your normal biological weight setpoint (interesting research points to how the hypothalamus regulates these set-points). Most people will find that they naturally bounce between a natural 5-10lb range. I speculate this is dependent on environment or the seasons...

@philipreal - Yes. Diet breaks every 8-12 weeks is good strategy. This is what bodybuilders do to help maintain muscle mass but also it helps to regulate some hormones.

In any case, much can be learned from those who actually lost a lot of weight (lost 30+ lbs) and kept it off in the long-run (maintained new weight for more than 1 year). The National Weight Control Registry (NWCS) is quite often cited in many studies and their registry has strict criteria (if an individual experiences a weight gain that exceeds the initial weight loss threshold, or if they stop reporting data, they are removed from the registry). For example, "78% eat breakfast every day."
http://www.nwcr.ws/

The National Weight Control Registry (NWCR), established in 1994 by Rena Wing, Ph.D. from Brown Medical School, and James O. Hill, Ph.D. from the University of Colorado, is the largest prospective investigation of long-term successful weight loss maintenance. Given the prevailing belief that few individuals succeed at long-term weight loss, the NWCR was developed to identify and investigate the characteristics of individuals who have succeeded at long-term weight loss. The NWCR is tracking over 10,000 individuals who have lost significant amounts of weight and kept it off for long periods of time. Detailed questionnaires and annual follow-up surveys are used to examine the behavioral and psychological characteristics of weight maintainers, as well as the strategies they use to maintaining their weight losses.

[delay]

I speculate this is dependent on environment or the seasons...

Definitely! Losing weight during the spring is much easier than during the winter.

[Stasher]

I'm on the opposite spectrum....

Rather than shaping my diet which to me is the hardest option I take the easier route. I instead go with staying very active and doing lots of activities daily like running, cycling and backpacking that make me sweat immensely, can last for 1 to 10 hrs in length and have done wonders for spiking my metabolism.

That way I can eat what I like (I just keep the junk food out of the diet) and maintain my weight easily. I find individuals that try for to long to reduce their weight by limiting calories end up hitting an unhealthy plateau due to metabolic adaptation in the wrong direction. Your body tends to get in a scarcity scenario and slows down your metabolism in an effort to preserve fat stores cuz "this person doesn't want to feed us and I don't know when energy is coming again."

I know this isn't really helpful on what or how to eat but from owning a gym in the past and mixing in a history of competing in bodybuilding and now the opposite extreme if focusing on endurance sports, I have seen way to many people fail only focusing on restrictive diets in real life.

[delay]

That way I can eat what I like (I just keep the junk food out of the diet) and maintain my weight easily.

Thanks for sharing!

For me adding junk food doesn't seem to matter as long as I eat whole foods. If right, it's not about skipping the bad food, but about not skipping the good food.

My body needs "non eating time" to keep a healthy weight. When I don't eat for 16 hours my body gets around to cleaning up excess fat. At least that's how I rationalize intermittent fasting.

Many people with healthy weight never exercise. It seems that exercise is not strictly required.

[Lemur]

Regardless of the dieting strategy, fundamental principles have to be followed but also important to recognize there is not a one size fits all approach. Can't break physics anyway. What quite often happens is a person loses weight with one strategy, believes this to be the most effective, then gospels that to others, only to be surprised with tons of anecdotes from others about why such and such doesn't work for them. Some in the dieting world might even discount someone elses experience altogether.

@delay

Yes exercise is not strictly required to lose weight but research does show that starting up exercise, especially after weight loss, is a good way to maintain the new weight. Exercise in of itself does not burn all that much calories unless you do a lot of it, and when people do deliberately use exercise to burn calories, they end up making up for the energy loss subconsciously by tuning down non-exercise activity thermogenesis (NEAT). For example, they might pace around less, twitch less, fidget less, not bounce there leg up and down while sitting, etc. Overall less micromovements.

https://en.wikipedia.org/wiki/Non-exerc ... rmogenesis

Our bodies are very creative energy saving machines primarily geared towards survival .

@Stasher

I think that is useful. I've read about strategies where some don't lower there food intake at all but just increase fun activity so most of the caloric deficit is created through activity as opposed to food restriction alone. There is more of a positive affirmation of what I am gaining versus a constant thought process of what I am losing.

A 500 caloric deficit, for example, can be acheived from either food restriction alone, ramping up activity alone, or practically some combination (maybe I burn 300 calories off maintenance today with a jog and 200 through food restriction). Whether one wants to track calories or not is totally up to them. I'd advise it at least for a few weeks though for beginners just to get an understanding of what is going in and what is being burned. With enough experience, most don't necessarily need to track calories unless they just like the data. Just like how most of us don't need to track our budgets down to the penny (I know what my income is and I know what I spend) but it is useful for those starting out. To me, I like tracking anyway so it is not a problem.

Regarding a focus on restrictive diet - I am mostly in agreement. These set most people up to fail. But there are cases where a restrictive diet can be very useful initially to reset taste buds and other habits. For instance, someone might find that no amount of flexibility can stop them from binging on chips (maybe that is a trigger food for them) or they've a sweet tooth. In these cases, best to be restrictive in some areas and flexible in others.

[delay]

Can't break physics anyway.
...
Our bodies are very creative energy saving machines primarily geared towards survival .

Thanks for your reply! The analogy with physics is I think unfortunate. "Food calories" are nothing like "mass". Mass has a strict definition and its preservation is easy to test and holds to high precision. Food calories are an estimate of the energy an average body will extract from a certain food. No two experts arrive at the same number. Testing "preservation of food calories" is not easy, in fact, the entire concept is not wel defined enough to test. Like, how many kilograms will I put on if I overeat 500 calories a day? The theory won't say. And experts just make up things to justify what was observed: maybe I moved more, or I had micro movements, or my body is just special. With these facts one would expect that the theory of food calories is useless. That certainly is my experience

One easy way to see this is the condition of diabetes. The affected people cannot create insulin and so cannot store fat. This means that the body can regulate fat storage. In other words, storing fat is a choice the body can make, not a "physical truth" that corresponds exactly to the food you eat.

[2Birds1Stone]

Some of the biggest breakthroughs in nutritional science over the past decade have been around the calories in vs. calories out debate.

While excess caloric restriction for prolonged periods causes metabolic adaptation, excess activity for prolonged periods causes almost as much metabolic adaption to the activity being done.

This can be observed with things like step count. If you go from walking 5k steps a day to 10-12k steps you will see a nice boost in NEAT. If you go from 10-12k to 20-25k you will see a short lived burst in caloric expenditure but your body will become more efficient and over time the extra calories burned from those extra steps becomes negligible. It's quite a steep curve as you increase past that.

Excessive exercise can also cause people to reduce their NEAT unintentionally. Work out hard for 2-3 hours, then you become a sloth the rest of the day.

I'll try to find the podcast episode with Dr. Trexler discussing this phenomenon.

[Lemur]

Thanks for your reply! The analogy with physics is I think unfortunate. "Food calories" are nothing like "mass". Mass has a strict definition and its preservation is easy to test and holds to high precision. Food calories are an estimate of the energy an average body will extract from a certain food. No two experts arrive at the same number. Testing "preservation of food calories" is not easy, in fact, the entire concept is not wel defined enough to test. Like, how many kilograms will I put on if I overeat 500 calories a day? The theory won't say. And experts just make up things to justify what was observed: maybe I moved more, or I had micro movements, or my body is just special. With these facts one would expect that the theory of food calories is useless. That certainly is my experience

One easy way to see this is the condition of diabetes. The affected people cannot create insulin and so cannot store fat. This means that the body can regulate fat storage. In other words, storing fat is a choice the body can make, not a "physical truth" that corresponds exactly to the food you eat.

@delay

I want to assume you're responding in good faith but I lost count of the strawmans? Like, for instance, I never claimed that "food calories are nothing like mass." There is a common misunderstanding of how energy balance works in the body. But do understand that it is physics, it is chemistry, it is a law of thermodynamics and it is directly measurable. https://youtu.be/nM-ySWyID9o?si=04TpwDeboOBbR5Jv And there is tons of good resources if you want to explore further: https://www.stephanguyenet.com/does-ene ... e-obesity/ .

Food calories measure energy. Just because something is harder to measure precisely doesn't make the concept invalid. Saying “experts just make things up” when predictions don’t match your expectations ignores the complexity of the system.

Yes - fat gain doesn't always line up perfectly with calorie surplus because our bodies are in a constant state of flux to maintain homeostatis...this doesn't invalidate conservation laws. You can't simply ignore all the measurable phenomena that makes that so: whether it is metabolic adaptations, increased/decreased movements, changes in gut microbiome, digestive changes, etc. Take an apple that has 80 calories for instance or even just use the 500 calories we spoke of. In the short-term, 10 different people will either burn or store this energy in some mix differently depending upon many many variables. Someone who just did some hard exercise will burn a lot of it for energy needs quickly...a sedentary person with maxed out glycogen stores will store much of it as fat. The fact that the body adjusts depending on its current needs doesn't mean the energy isn’t conserved; it just means it’s being utilized or stored differently. In the long run, the math adds up and you will either gain weight or lose weight in the long run depending on the difference between energy stored and energy burned.

Your strawman about diabetes is also misleading. Yes, people with untreated type 1 diabetes lose fat (and muscle) because their bodies can’t store nutrients due to a lack of insulin, but this is a short-term pathological state that quickly leads to death when untreated and is not a free pass to override thermodynamics. Once treated with insulin, they gain fat like anyone else (sometimes even rapidly). And people with type 2 diabetes who have high insulin and insulin resistance gain fat all the time. Where do you think the excess glucose goes? If fat storage were just a “choice” the body makes, this wouldn’t happen. The body doesn’t get to opt out of energy laws.

So yes, thermodynamics matter, we're fortunate to have the physics, and calories matter. Calories are not always perfectly measurable or predictive at the individual level over short timeframes, but they hold true in long timeframes, and dismissing the whole concept because it’s messy is like saying gravity doesn’t work because you don’t know the exact speed of a plastic bag blowing in the wind and the bag isn't moving like you expect it to. It's not the theory that's flawed; it's the expectation of precision in a system with hundreds of moving parts.

[Lemur]

Some of the biggest breakthroughs in nutritional science over the past decade have been around the calories in vs. calories out debate.

While excess caloric restriction for prolonged periods causes metabolic adaptation, excess activity for prolonged periods causes almost as much metabolic adaption to the activity being done.

This can be observed with things like step count. If you go from walking 5k steps a day to 10-12k steps you will see a nice boost in NEAT. If you go from 10-12k to 20-25k you will see a short lived burst in caloric expenditure but your body will become more efficient and over time the extra calories burned from those extra steps becomes negligible. It's quite a steep curve as you increase past that.

Excessive exercise can also cause people to reduce their NEAT unintentionally. Work out hard for 2-3 hours, then you become a sloth the rest of the day.

I'll try to find the podcast episode with Dr. Trexler discussing this phenomenon.

@2Birds1Stone

Yes thanks for sharing this - Herman Pontzer also explores this in his book "Burn" that is an excellent read https://www.amazon.com/Burn-Research-Re ... 0525541527

Also regarding the CICO debate ...trying not to beat a deadhorse but its definitely been more than a decade
https://youtu.be/9fxji5xkXOA?si=VAVXGkvg2PpSsBxq

I truly believe that dieting is not always meant to be easy and this is a hard truth for too many to accept...which is why basic first principles like thermodynamics get tossed out the window by the masses. The misunderstandings of energy balance make it all too easy for marketers, tricksters, and charlatans to sell ideas and products that can magically cause fat loss without effort.

[delay]

The body doesn’t get to opt out of energy laws.

Thanks for your reply. Physics states its laws in mathematical expressions. So you get kinetic energy, potential energy, work done by nonconservative forces, and so on.

Now the food people use words from physics, but that doesn't mean these words then have the same authority as when they are used in physics. For example, you use the term "energy law". What law do you mean? What is its mathematical expression?

Or even more basic, how is the food calorie value of a particular package of food determined?

[Lemur]

Thanks for your reply. Physics states its laws in mathematical expressions. So you get kinetic energy, potential energy, work done by nonconservative forces, and so on.

Now the food people use words from physics, but that doesn't mean these words then have the same authority as when they are used in physics. For example, you use the term "energy law". What law do you mean? What is its mathematical expression?

@delay

When people argue calories in vs. calories out and they talk of energy laws, what they're referencing are principles from thermodynamics, specifically the first law which states that "energy cannot be created or destroyed, only transformed from one form to another." Applying this to calories: if you consume more calories than you burn, you will gain excess energy usually stored as glycogen, muscle tissue or organs, fat, ligaments, etc. If you burn more calories than you consume, your body uses stored energy (fat, glycogen which is just stored glucose chains, and sometimes even muscle) to make up the difference. This forms the basis of calories in vs. calories out.

Energy inputs come from the foods you eat measured in kilocalories. This is the energy needed to raise 1,000 grams of water by 1 degree Celsius. When food labels use "200 calories" they're really displaying 200 kilocalories. 1 gram of fat is 9 calories, and 1 gram of carbohydrates or protein is 4 calories.

Energy outputs are combined to form an individual’s total TDEE (Total Daily Energy Expenditure). Major outputs include the following:

• BMR (basal metabolic rate): energy to keep you alive at rest. Like breathing, heart pumping blood, brain, etc. Makes up 60-70% of output.
• TEF (thermic effect of food): energy to digest and process food. Makes up 5-10% of output.
• TEA (thermic effect of physical activity): energy to perform exercise and daily movement. Ranges from 15-30% depending on your personal activity levels.
• Non-Exercise Activity Thermogenesis (NEAT): energy used from fidgeting, walking, micro movements, etc.
• Adaptive Thermogenesis and other biological adaptive components - makes up the rest of the energy used and is regulated by the brain but mostly represents changes in energy use due to factors like cold, starvation, but also to conserve energy. Can call this the adaptive component or adapt.
• There are a couple of different formulas developed over the years to help you get an estimate of what your own TDEE might be if you're curious. Like this calculator can be used: https://tdeecalculator.net/ . Remember these are starting points and estimates and should be adjusted by real world changes.

So an energy surplus results when food eaten (measured in calories) is greater than the output of (BMR+TEF+TEA+NEAT+Adapt). And vice versa for energy deficit.

Gaining weight results from a calorie surplus: Food eaten > TDEE.
Losing weight results from a calorie deficit: Food eaten < TDEE.

I know it sounds a bit like an Occam's Razor and maybe that is why people generally get skeptical and I think that is due to the tons of caveats that people get caught up on that cause endless debates about this model because there is a misunderstanding that the CICO model is a dynamic system (it isn't static). For example, you've metabolic adaptations when weight changes from long-term calorie surpluses or deficits. Hormones like insulin, ghrelin, leptin can affect how energy is utilized and stored, and effect signaling of hunger to the brain. Food quality affects satiety and some macronutrients like protein, for instance, have higher thermic effects than carbohydrates or fats. Or fiber can help flush calories literally down the toilet. But none of these details invalidate energy laws.

So weight gain or loss is ultimately determined by energy balance, but there are many variables that effect both sides of the equation: both inputs and outputs.

Or even more basic, how is the food calorie value of a particular package of food determined?

https://www.sciencedirect.com/topics/en ... alorimeter

[delay]

When people argue calories in vs. calories out and they talk of energy laws, what they're referencing are principles from thermodynamics, specifically the first law which states that "energy cannot be created or destroyed, only transformed from one form to another."

Thanks for your reply. Thermodynamics deals with heat and work and temperature, like the expansion of a gas when you heat it up. Thermodynamics deals with dead matter.

When life comes into the picture thermodynamics becomes less useful. Life is transformation, one living being's output is another living being's input. The water that is pissed out by a cow feeds gras; a dead body is consumed by vultures; dead plants compost and become food for other plants. It is all organic chemical reactions. Many of these reactions dissipate energy in the form of heat. There is no shortage of energy because the sun keeps the show running.

Gaining weight results from a calorie surplus: Food eaten > TDEE.

Living organisms can make choices. The muscles of the intestines can speed food through or slow it down, resulting in wildly different absorption rates. Sugar in the blood can be stored as fat, it can secreted by the kidneys and pissed out, it can be used to expand muscles, do maintenance work, heat the body, shiver, and so on.

If my intestines ignore food and poop it out, how can that result in higher weight? If my kidneys secrete the sugars and piss them out, how can that result in higher weight?

So weight gain or loss is ultimately determined by energy balance, but there are many variables that effect both sides of the equation: both inputs and outputs.

While living matter has to obey the laws of physics, it's complex enough to make thermodynamics practically useless. This is reflected by the variables you list that make up the TDEE. None of them can be measured. There are no testable predictions.

https://www.sciencedirect.com/topics/en ... alorimeter

That's interesting, as far as I read, it was estimates by diet experts. So what they do is burn food and see how much energy it releases? I guess that's a form of upper limit. Luckily humans do not burn their food, and our poop is much more useful to other life forms than ashes.