Ah but there is a bit of truth behind the assertion, at least the actual assertion I have heard made (which is not how you have apparently heard it). See here. Very strict calorie restriction significantly decreases resting energy expenditure (the effect of calorie restriction on other aspects of energy out, such as non-activity thermogenesis, aka NEAT, is a whole separate subject), while running a more moderate calorie deficit does not. The result is less fat loss than the calorie deficit would otherwise be predicted to cause. No, not none, but less progress than such a deficit would be expected to cause. Notably in that study the 500 kCal/d group ended up after 24 weeks with only marginally more weight loss than the 1200 kCal/d group did: 12.1 to 10.6% of body mass.
Thank you for saying that. There was someone in a recent thread who was making the same assertion and it was most frustrating. If you look at the numbers in DSeid’s link, the comparative groups were both on extremely low calories. The ‘well fed’ group was getting only 1,200Kc and the really starving group were on 500Kc per day.
The latter restriction is of course completely unrealistic compared to ‘real life’ - very few people are actually going to be able to restrict themselves to that order of reduced intake unless they practically fast*. And even though the amount of body mass both groups lost was relatively similar, they did actually both lose more than 10% of their body mass even with a greatly reduced BMR - albeit it took 24 weeks for it to happen. And a horrible and disappointing six months they must have been for just a 10+% weight loss.
My point in a previous thread was that to lose fat weight, you are inevitably going to ‘starve’ a little bit because you need to manipulate your body, through whatever mechanism, into turning some body fat into fuel to supplement a calorie deficit from reduced ingestion.
In other words, every single successful fat burning diet has elements of ‘starvation’. Yet many people (including myself) have in fact managed to lose a substantial proportion of body mass by eating less, and did not suddenly switch into a magical mode where the body can conjure energy out of thin air.
‘Starvation mode’, while it clearly does exist in extreme circumstances, appears to be much exaggerated by people who have been unsuccessful in reducing their calorific intake vs their BMR, and perhaps didn’t have enough patience.
I contend that misinterpretation of ‘starvation mode’ is a notion that is growing in prominence and probably stands in the way of many western people’s success in substantial weight loss.
*I fasted for a week once to see what it would be like. I only lost 2lbs - presumably because I was truly in starvation mode.
I have another speculation here to throw out:
When an overweight person first begins to diet, they train themselves to eat smaller portions. It’s a pain and when they weigh themselves and see that it’s having an effect, their natural reaction is to go “Woo hoo, it worked! Now I can get off this damn diet and increase my portion size a bit! 
:D”
Sadly, the absolute opposite is true. As your bulk reduces, the amount of energy required to maintain it also reduces. I.e. your BMR (as well as calories burned during weight-bearing CV activity) reduces along with your weight.
Therefore what really needs to happen is “Woo hoo it worked! Now I have to reduce my portion size again. 
:(” And this needs to happen over and over again as long as the person’s body mass reduces.
I have certainly observed this tendency in myself and wonder if it’s fairly universal?
And if so, perhaps this accounts for the exaggeration of ‘starvation mode’?
AFA the math goes, the gist is that A is kept separate from B. a1…a10 are all consistent, b1…b10 are all consistent, but the two sets conflict with each other. A->B is like a circuit that allows communication between the sets, which can kind of wreck them both. Denial involves keeping that circuit open so nothing may pass. Which may be interpreted as irrational behavior.
I think of cognitive dissonance as the clashing part of it. The sound of A and e-flat together. The CD theory is rather broad. I think cognitive dissonance describes pretty well most of what I am getting at with my theory of denial. I’m viewing the dissonance as the motive for the denial.
‘Motive’ isn’t the best term. It implies something conscious, an intentional deed. I wonder if it cannot be conscious because otherwise the person would simply realize A->B. So perhaps it must be semi-conscious or sub-conscious. I think this can easily happen if it is the brain itself, acting as a bodily organ, which has the aversion to dissonance. It would rather not be bothered with clashing all its constructs against their opponents.
I also want to add that people who can’t lose weight might not be in denial. I am simply interested in the subject right now.
I can lose weight.
Of course I can lose weight. After all, the math is there: decrease calorie intake and increase calorie output. Reduce simple carbs. Increase protein. Eliminate saturated fats. Enjoy polyunsaturated fats. Eat lots of vegetables, some fruit, and skip the grains. Build muscle through strength training to increase basal metabolic rate. Journal food and water. Exercise 30 minutes a day.
On any given day, I run about a 15% chance of actually managing to pull off the above, even though I know exactly what I need to do. Why?
Well, let’s see:
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My schedule wreaks havoc with my ability to plan and commit to anything, let alone a challenging course of diet and exercise.
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My bouts of severe depression with occasional suicidal ideation literally reduce me to rating “lying curled up in a ball, not hurting myself” as my big accomplishment for the day.
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Even when I’m not dealing with suicidal ideation, intrusive thoughts of hurting myself, obsessive thoughts about how much I suck and don’t deserve to be happy, the smallest emotional upset can and will throw me off my game for the rest of the day.
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My self-medication of choice is (you guessed it!): eating. When the pain gets too bad, I have a handful of choices. I can take some of my prescription medications inappropriately. Take someone else’s prescription medications both inappropriately or illegally. Drink alcohol. Have an emotional meltdown that does enough damage to my social/financial/work life it takes a year to repair. OR I can sit down and consume 3000 calories of salty, fatty, sugary food that lights up my limbic center like a Christmas tree and causes every dopamine receptor in my brain to yell “BINGO!”
That’s not even including external stressors like my father, who has mild to moderate vascular dementia, my employment (or lack thereof), my finances (or lack thereof), or my social life (or lack thereof).
Yes, like all humans, I have the ability to lose weight when I reduce my calorie intake and increase my calorie expenditure. What I can’t do, at this time and for the foreseeable future, is get my shit together enough and dig up the internal resources - focus, perseverance, foresight, willpower, et al - and apply it to the problem of weight loss consistently enough to do any good.
Therefore, no, right now, I can’t lose weight.
I’ve read the weight loss threads with great interest, especially over the past year as my weight has slowly crept up. I’m 44 and was unpleasantly surprised to enter perimenopause a little over a year ago. Now half the time I’m either hostile, craving salty foods or brownies, wired up and talking incessantly, or sad because nobody likes me. What fun! In the meantime my jeans are getting too tight and not in a good way.
I can’t talk about it much IRL because I’m 5’ 7" and currently weigh about 155. When I bring up that I’m uncomfortable at this weight, friends usually tell me to shut the hell up. I think what it comes down to is that I’m getting older, things are getting squishy and I don’t like that at all. So, off to the gym. I sleep better and the restless legs thing has gone away. I’ve only been going for about a month so it’s too soon to see anything too noticeable, but I have noticed that I jiggle less when I jog.
I have low blood pressure, it runs in the family. A good defense mechanism to ward off the exhaustion this brings is to snack frequently. For at least the past 25 years I’ve been in the habit of ‘grazing’ all day. For breakfast today I had an apple and a handful of nuts. Lunch will be 1/2 sandwich and some soup. When we have dinner my portion looks like it’s for a kid. In between I eat string cheese, carrots, crackers, nuts, fruit, an egg or two, etc. Sometimes chips or a doughnut during certain times of the month, I’m all GET THE HELL OUT OF MY WAY AND HAND ME THAT CHOCOLATE FROSTED DOUGHNUT OR I SWEAR I’ll HURT YOU. These habits have more to do with how food makes me feel than any diet I specifically follow. If I don’t snack on healthy, protein snacks I feel like crap. Since I don’t like to feel like crap, I try to behave.
My sister is 10 years older than me and weighs about 130. Oldest brother is tall and skinny. Other brothers are athletic and average. I really do believe that genetics have a lot to do with weight.
Anyhow, restaurant portions are huge and I’m amazed when I go out with the girls to see how much they can eat. I know I’m on the other side of weird on this one, but there is no way in hell I can put away soup, a salad, an appetizer, a full meal, a few drinks, etc. It feels like there’s no place else to put anything after just the soup and salad. Honestly, that’s what keeps me from getting big. My capacity seems to be smaller than the average bear. Even so, years of a mostly sedentary lifestyle have taken their toll.
Like I said, I don’t feel comfortable talking about this, except here. I’m not obese but am not happy with this weight but can never talk about it IRL because people don’t want to hear it. Maybe you don’t either, so I’ll stop now.
I get mildly irritated by the “I can’t lose weight crowd”–but I also feel bad for the people who suffer in silence for years and years, eating bland/frozen diet food, and struggle with their weight all the same, all because both groups refuse to work out. Of course there are exceptions; some who claim they can’t lose weight actually can’t due to physical limitations. Others actually do work out and it’s just not happening for them. But in my experience, people want the easy way out, which means refusing to partake in strenuous physical activity.
I’m 33 and measure in at 6’2", 190 lbs. My doctor has recommended that I lose 10 lbs, since I’ve put the weight on in the last few years. No sympathy for me at that height/weight, of course, and it’s been hard for me to shed those 10, but I know that if i were to adopt even a semi-regular regimen of exercise, that weight would come off rather quickly.