Hi Honey, I didn't think the questions weren't valid, I said it was a merry go round because I didn't think we were getting anywhere, and Grinch seemed to be taking the discussion personally, and I kind of got the feeling from what he said, that he had his mind made up. If he hasn't, fair enough, happy to take that comment back. And as I've found myself in the past, its important to try not to take these debates personally - we're discussing ideas, and science and health with people around the world - how great is that!

Personal experience does have to be taken with a pinch of salt - but many, many correlational studies on diet and health are carried out with personal reporting of food intake and exercise level - so a lot of the science involved is also debatable. I didn't take offence at Grinch not believing my account or PJ's account - we're just words on a screen, we don't know each other.

As I said, the point at which metabolism will slow down, will be different dependant on lots of factors - how much weight there is to lose, metabolic damage, hormonal factors, insulin resistance, level of exercise, other health issues, medications, thyroid etc, and it will be different for each person - there is no set number of calories for every person of the same weight.

Short term on very low calorie, a person with excess fat will lose weight, medium term they will have their metabolism slow and weight loss will stall or slow, long term the weight will come off until a point that it either stops due to reaching a balance, the calories increase, or you die of starvation. 600 calories a day will take a long time to kill you, though the nutritional deficiencies and muscle loss will be damaging.

The sticking point seems to have come over the subject of exercise intensity and Grinch considering energy level while exercising and BMR to be interrelated, him making the point that he feels his energy levels while exercising would drop if his metabolism slowed. My argument was that the body was adaptive and wants to survive above all else, and wouldn't limit your ability to intensively exercise until way along the route to starvation (YMMV), because lowering ability to undertake physical activity would have meant death during times of famine - and this appeared to be our sticking point, from my point of view, with Grinch insisting that if a person can exercise at high intensity it equalled no drop in metabolism (if I have this wrong, please correct me). And although I agree that someone eating very low calorie can experience a drop off in ability to intensively exercise due to reduced metabolic rate - an ability to continue to be able to exercise intensively does not mean that there has been no drop in metabolic rate due to the very low calorie diet. Yes, eventually, your body will have no choice but to put the brakes on - but where this is in the process will vary with the individual - how much excess fat they have, what type of exercise they're doing, when they're exercising in relation to calorie intake, whether the person has any high calorie days interspersed with the low calorie ones - which can help to maintain metabolic rate. Although exercise can increase metabolic rate for a short time, if calories are very low, I expect energy conservation to kick in pretty quickly - it would be during the rest of the day you might feel sluggish.

My personal opinion on the whole starvation mode, calorie intake thing, is that you need a deficit from your BMR, which will vary according to exercise levels, but it shouldn't be too much - no more than about 500 calories, maybe 700 at a push. Exercise shouldn't be too intense with emphasis on weights and resistance work to minimise muscle loss. Every so often, once a week or fortnight, have a really high calorie day to keep the metabolism guessing and thinking that there's still aedquate food sources around. Barring other issues (thyroid, hormones etc) this should stop any big drops off in metabolism - though of course BMR will drop naturally as weight drops.

Anyway, it is midnight here, and I've eaten about 700 calories today because I forgot to eat dinner (oops). Off to eat something so that I can take my meds.

Lee

Thanks for taking the time to respond to the thread again, Lee!

Omigosh... where to start,... where to start??

Your post had so, so many great points in it that I agree with, that I definitely am not going to copy and requote each section and repost it with 'likeys" and "I agrees", because I think it would be too long to duplicate so much again.

BUT, I really emphatically agree with this point in particular,


I thought this was hidden enough, amongst so many other salient points, that it was worth pulling out and and showing again on its own.

I also, wholeheartedly, agree with this!



What a great, great concluding paragraph, for your post! A succinct summary, of what I consider to be perhaps amongst the 3 biggest takeaways of all, to keep in mind...and *I* think, true for all LCers!

SUPER!

My colleague Gene Fine and I addressed this question in a couple of papers. Of course, partly it is a question of numbers -- if you are in starvation, you will lose weight but it may be at a different rate than somebody else. The fallacy in the calories in-calories out idea is first, as you say, that it ignores the 2o law, but also, you have to remember that the formalism of thermodynamics as we use it is equilibrium thermodynamics and living systems are far from equilibrium. Non-equilibrium thermodynamics recognizes that rates become important too. We provided a description of the problem in a paper in Theoretical Biology Molecular Models (available without subscription at http://www.tbiomed.com/content/pdf/1742-4682-4-27.pdf ). In that paper Figure 1 tells the story: if you slow the break-down of fat sufficiently due to a particular hormonal state, you have to eat little to maintain fat compared to someone who is in a different state. The rest of the paper is not necessary to read; Figure 1 tells the story. There are actually other fallacies and, in general, the real question is why, to a large extent, day in and day out, for most people, a calorie is a calorie while thermodynamics actually predicts great differences in efficiency. The answer is that this is the unique feature of biological systems. In fact, the first law doesn't even apply as I explained in my blogpost at http://wp.me/p16vK0-5S. The real problem is that thermodynamics is a tough subject and those of us who have actually studied it are amazed at how it is thrown around by non-experts. Anyway, hope this helps.
Richard David Feinman
Professor of Cell Biology
SUNY Downstate Medical Center

Thank you Dr Feinman!! Much appreciated!

And... taa daaaaa! Our knight in shining armor has arrived!



LOVE this!!! (I'm always particularly smitten, with anyone's ability to point out something so concisely, that I could only ever dream to!)

I am responding to your post before I have even had a chance to click on your paper,...which I am going to do right now.

I just wanted to say a big, big thank you to you, Professor Feinman, for adding to this thread, and for helping to keep it going!

Like I said before... I am really enjoying this one!

Great to have a scientist weigh in!

Lee

Thanks Dr. Feinman. I had read a few of your things online before but not that one.

I found the "non-equilibrium" perspective to be very interesting. It seems to me that most everything in humans happens in major cycles -- sleep and eating-related biochem changes to begin with.

It got me thinking while reading, wondering if there is some kind of basic principle that if something MUST be kept in equilibrium (for example blood pH), if that kind of de facto implies that the things which act upon it are going to be very "non-equilibrium" in nature, as part of the constant attempt to 'compensate for' everything, to keep that one thing at a set place.

It's a pleasure to realize that people have got a clue and a place to begin with this topic. Although getting enough of the rest of the world on the same page to include funding is another story alas!

PJ

And that would be correct.

http://www.youtube.com/watch?v=M6vpFV6Wkl4
At the 39:00 mark, Taubes explains the caloric balance equation.

Ein and Eout constantly adapt to each other.

It seems rather contradictory that you first say you don't believe starvation mode exists, but then say Eout must adapt if Ein drops so low. Starvation mode is Eout adapting to Ein.

Doesn't it seem strange to you that a fat person who has a surplus of energy is lethargic, while a lean person who has only enough energy is much more active?

It's important to remember that low calorie diets are basically lower carbohydrate diets. That's because since the starting diet is already low fat, the only significant source of calories we can cut is carbs. As most of us have learned from Atkins and Taubes et al, it's all about hormones and primarily about dietary carbs.

If we consider that what matters most is not how much energy we eat, but rather how much energy is available to use, then we could say we are already in starvation mode on a high carb low fat diet. That's because the carbs keep insulin high, which locks energy in fat cells, and because there's only a little dietary fat coming in. We have ample evidence of this with Ancel Keys' Semi-Starvation experiment, or the Chris Gardner A-TO-Z study for example. The Keys study shows us that starvation mode exists and its effects are real. The Gardner study shows us that it affects how much energy we spend, as shown by the differences in weight loss between the study groups. It also shows us that starvation mode is less likely to occur on a low carb high fat diet.

Have you considered the effects that different intensity has on hormones? Lifting heavy weights for example will stimulate a greater GH secretion than a slow jog. GH acts on adipocytes directly. This has an effect on body weight. So while it might look like you're spending more energy with HIIT and you believe that's why you lose more weight with it, it's actually not about Eout, but about the effect of HIIT on GH and the subsequent effect of GH on adipocytes.

Compare the two hypotheses:

HIIT => Eout goes up => adipocytes respond by shrinking.
HIIT => GH goes up => adipocytes respond by shrinking => Eout goes up.

How can Eout go up before adipocytes release more fat? Even if Eout goes up in every other cell before adipocytes shrink, how are adipocytes told to shrink after that? No, it's much more plausible that HIIT has an effect on GH, which then has an effect on adipocytes, which ultimately causes Eout to increase.

What would happen if GH did not go up in response to HIIT?

Calories and exercise aren't the only things that change on the Biggest Loser. The whole environment changes. And, Jillian perching on the console of your treadmill and screaming in your face might have some hormonal effect conducive to weight-loss.

The fact that when subjected to that kind of treatment, people lose weight doesn't determine that they could have just quietly decided to move more and eat less at home and had similar results. Or that they would be at all likely to make that decision. Supposing just for a moment that a person's metabolism actually slowed down to six, seven or eight hundred calories a day. I have no idea how slow a metabolism really can get, and the person still live, but suppose. I think I'd have to suppose that that would extremely limit their motivation to start exercising to keep their metabolism going. Absent prison guards, would it even happen in most cases?

Homicidal: the ultimate state for making energy available to man.

PJ

Thanks for positive feedback from everybody. On the question of de facto reduction in carbs, that is, when you reduce calories, some comes from reducing carbs, raised by M Levac, sometimes, weight lost is less of an indicator of metabolic change than other things like, for example, triglycerides. In the A-to-Z study, the values for carbohydrate consumption for each diet are given. If you plot CHO for the three time points for each diet against triglycerides, you get an amazingly straight line over all diets and a wide range of carbs clearly pointing out how metabolism can be controlled by dietary carbs. The results are statistical and there are obviously other factors that affect weight loss. I published this graph some place. Will try to find and post a link.