This is definitely true, if you eat less calories than you burn, you will lose weight. But this is really hard to enforce for many people. Without blatant calorie labels on everything you eat, it's really easy to go over and then assume that it must not be true.
The human body is more complicated than that. Different foods cause different levels of insulin response. Insulin tells the body to "pack it away as fat." As mentioned in the article, it's likely insulin is more relevant to heart disease than saturated fat intake.
The role of insulin also helps to explain obesity observed in malnourished populations, people who simply aren't taking in enough calories to get fat, but are.
I also take issue with your message toward people who are struggling with overweight. It's not just that overweight people are bad at staying within limits; it's that fat cells stimulated by insulin to grow send messages requesting more energy, stimulating appetite.
You can't not lose weight if you burn more calories than you eat. Where does the extra energy come from? I'd like to see examples of overweight people that are malnourished in the sense that they don't eat enough calories.
I fully support the claim that some foods make you more hungry than others, even if you eat the same amount of calories. It'd be pretty hard to consume 2000 calories of spinach without rupturing your stomach, but it's easy to eat 2000 calories of chocolate chip cookies with milk.
First, metabolic rate is not constant. If you feed your body few calories, your metabolism adjusts so as to use few calories. Fat cells that are stimulated to grow scream loud for their share of the energy, ensuring that they get their needs met even if the rest of you is weak, tired, and resorting to stealing energy from muscle and other tissues. This is not a zero sum game. Certain conditions may cause someone to retain water, which can add to weight independent of calorie consumption and use.
As for examples of obesity occurring concurrently with low caloric intake, take the Pima native Americans in 1905, where most of the obesity is in women, who were quite physically active, basically treated like beasts of burden. You can find the same trend in 1928 with Sioux on a South Dakota Crow Creek Reservation--very high levels of obesity in coincidence with extreme poverty. In the early 1960s, MIT nutritionists calculated that Trinidadians were getting no more than 2000 calories per day, yet they were seeing an extreme obesity problem among the females.
> You can't not lose weight if you burn more calories than you eat.
True. However, you can eat less and not lose weight, or eat more and not gain weight, because while Calories Consumed = Calories Stored + Calories Expended, by the laws of thermodynamics, the variables are not independent. If you exercise more, your body acts to try to get you to consume more calories -- and if you don't, by making you not want to expend energy the rest of the day (some studies of kids exercise programs show that the kids become more sedentary the rest of the day). Further, the type of calorie consumed affects the balance of the other side of the equation as well.
20 calories a day is theoretically 40 pounds of fat over 20 years, but nobody can perfectly maintain their caloric input to within exactly 20 calories of maintenance level a day -- our body guides us with signals and changes our metabolism. The arguments about things like fat, carbs, etc. are that the wrong foods mess with these signals and the metabolism in ways that make it substantially harder to stay at a healthy weight or to lose weight.
>Effects of Dietary Composition on Energy Expenditure During Weight-Loss Maintenance
>The results of our study challenge the notion that a calorie is a calorie from a metabolic perspective. During isocaloric feeding following weight loss, REE was 67 kcal/d higher with the very low-carbohydrate diet compared with the low-fat diet. TEE differed by approximately 300 kcal/d between these 2 diets, an effect corresponding with the amount of energy typically expended in 1 hour of moderate-intensity physical activity
>In conclusion, our study demonstrates that commonly consumed diets can affect metabolism and components of the metabolic syndrome in markedly different ways during weight-loss maintenance, independent of energy content. The low-fat diet produced changes in energy expenditure and serum leptin42- 44 that would predict weight regain. In addition, this conventionally recommended diet had unfavorable effects on most of the metabolic syndrome components studied herein. In contrast, the very low-carbohydrate diet had the most beneficial effects on energy expenditure and several metabolic syndrome components, but this restrictive regimen may increase cortisol excretion and CRP.
I don't have that much time to look at the link, but at the first glance it appears that at least some of the studies reviewed relied on self-reported calorie intake, so the subjects were not kept in laboratory conditions where the food intake was strictly measured.
This has been shown to be widely inaccurate, for example here and in the references to this study
That, and the fact that most natural high carb foods, like fruits, vegetables, legumes and whole grains have a low calorie density compared to high fat foods. It's much harder to overeat on them, because they have more volume and fiber.
"most natural high carb foods ... have a low calorie density"
Need to combine with the equally true observation of most modern processed high carb foods have a ridiculously high calorie density.
Apples are only in season some of the year, so when you can get them, pig out, of course it takes a lot of work to find and harvest apples and the natural supply is fairly limited in quantity and your stomach can only physically hold so many apples ... and millennia later the same taste receptor and insulin feedback loops results in some dude drinking an entire 2 liter of corn syrup soda while sitting on the couch watching a movie.
When people recommend legumes, they're not normally talking about peanuts. It's like people recommending fruits aren't normally talking about tomatoes.
Note how peanuts and bacon have similar caloric densities, yet black beans, brown rice, oats, and corn are much much lower? These are the legumes and whole grains parent is likely talking about, not peanuts and whole wheat bread.
Note how even chicken breast and light string cheese are twice as dense as than those whole grain products.
Note how high water content fruits and vegetables are king.
It's actually pretty easy to do without food labels. Apply this simple test: are you feeling dizzy from low blood sugar and is your stomach hurting from hunger?
If yes, then congratulations - you're burning more calories than you're eating. If no, then don't eat for a while. If no and you're actually feeling even a little full, stop eating, right now.
You'll get used to the lower calorie input after a while and the feeling of hunger won't be as sharp.
It's actually pretty easy to do without food labels. Apply this simple test: are you feeling dizzy from low blood sugar and is your stomach hurting from hunger?
It actually wouldn't work in each and every case. I practise intermittent fasting, up to two days, and quite often I wouldn't feel dizzy and my stomach wouldn't hurt, at least as long as I have plenty of water. But I'm sure I'm burning more than I receive on fasting days!
As Evgeny says, fasting doesn't necessarily cause those symptoms. I've fasted for a day or two at a time as an adult (and about two weeks once as a fat teen). Hunger as a physical sensation is probably not usual thing to feel in the West (or, at least, in America). As an obese American, it takes more than 24 hours of fasting for me to be physically hungry; the vast majority of the time I eat for social reasons, or from boredom.
In my social circles, the most common response to a question about food is "I could eat" rather than "Yes, I'm hungry", since the latter is never literally true.
It is a strong argument and I know to many examples where this is just simply not the case.
I myself have been eating all my life big portions of food couple times a day, mainly with meat and potatoes, sometimes with some salad though a lot of times without any. I'm not a big fan of sweets, but I do eat bread and some other stuff containing carbs, simply because it is almost impossible to avoid it these days.
At the same time I'm developer spending most of my time in front of computer and I do not go to gym. It has been like this for the last decade, though in the last 5 years I have spent much more time in front of computer and much less doing anything else. Yet my eating habits hasn't changed, neither did my weight. Since I was 16 and my wight was always 90-95 kg, I'm >1.9m height. I believe that this case just proves that calories in vs calories out doesn't always apply. Otherwise by now I should be obese whereas nothing even remotely close has happened.
Don't forget that your basal metabolic rate is not constant in different circumstances and over the duration of your life. It actually goes up if the calories consumed go up. I guess in some lucky individuals it may go up high enough to offset all extra calories - but, surely, to a certain limit.
Also, this BMR varies between different people - even if their bodies are very similar. So that is probably the source of the confusion "i know this guy who eats all the time and is skinny, therefore the calorie theory is wrong".
This page has links to numerous studies that prove the calorie in - calorie out theory. As far as I know, this theory was not yet disproved by any clinical study.
> So that is probably the source of the confusion "i know this guy who eats all the time and is skinny, therefore the calorie theory is wrong".
If we have evidence that something isn't true, and we even have theoretical reasons why it wouldn't be true, why continue calling it "confusion" when someone points out that it doesn't seem true?
(By the way, no one, anywhere, is disputing the laws of thermodynamics when they say that "calories in / calories out" isn't the whole story.)
Except you don't. A guy who eats all of the time and is skinny has a high metabolism. That's still 'calories in' < 'calories out'. The reason it's being called 'confusion' is because someone has made the mistake of thinking 'calories in' = 'weight'.
>By the way, no one, anywhere, is disputing the laws of thermodynamics when they say that "calories in / calories out" isn't the whole story
That's precisely what they are doing. Metabolism, poor calorie absorption, exercise, etc all fall under 'calories out'. It is the whole story, it just doesn't provide a lot of useful details about how to boost the 'calories out' category.
Unless you are done kind of magical machine, or perhaps have some kind of digestive problem which prevents you extracting energy from food, then you are obviously burning the calories you consume.
Even given a relatively sedentary lifestyle, you probably require around 2500 calories a day to maintain your weight. That's actually quite a lot - it's perfectly possible that you don't consume more than that with a couple of big meat-and-potatoes meals every day.
Things like alcohol, soda and snack can add huge calorie counts, and I suspect that in many people these are the factors that are causing weight gain. Have you ever actually added up your calorie intake for a day? It might be lower than you think.
I've been 1.8m and 64kg since I stopped growing. I know I overeat most of the time. Where does the additional energy go? Why is it stored as fat in some people, not in others. There is more to health than simple calories in = calories out.
Can you run us by a typical day of food? I'm not discrediting you, but from experience, what for you is overeating, for others is considered undereating.
This is definitely true, if you eat less calories than you burn, you will lose weight. But this is really hard to enforce for many people. Without blatant calorie labels on everything you eat, it's really easy to go over and then assume that it must not be true.