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
|