Message Boards » Fitness and Exercise

TOPIC: Negative Net Calories?

« Prev 1
« Prev 1
 
Ic_disabled_photos
Topic has been inactive for 30 days or more and images have been disabled.
Display All Images
July 15, 2012 6:51 PM
Has anyone had a negative net calorie intake day. I would like to hear about it.
  23889184
July 16, 2012 5:31 AM
Thats never good means you didn't eat enough food for the day.
July 16, 2012 1:17 PM
Yes I have them all of the time. I work out three times a day averaging burning 550 each time. In take in 1500 calories per day. I am trying to figure out if that is harmful or not.
July 16, 2012 5:15 PM
Today I ate 1258 and burned 1457. Probably couldn't do that everyday but on days I feel like working out more I do it.
July 16, 2012 5:30 PM
Your body needs calories to function, they're energy for your body. If you exercise below what you eat you're not leaving anything for your body to use.
July 16, 2012 5:41 PM
A good rule to follow is to find your BMR, and then don't net below that. BMR is the amount of calories your body burns just existing, if you were comatose and did nothing all day. If you are netting negative calories, it means you're not even giving your body the fuel it needs to exist, let alone to do those high burn workouts.

Great topic here with tons of info on figuring out your target calories, body weight, etc, and keeping yourself healthy in the process: http://www.myfitnesspal.com/topics/show/654536-in-place-of-a-road-map-2-0-revised-7-2-12
  6941661
April 5, 2013 10:32 AM
QUOTE:

Has anyone had a negative net calorie intake day. I would like to hear about it.


The proper question here is not whether negative net calories can hurt you, but over what period will that negative net caloric intake be harmful. Unless you are already underweight it is unlikely that having a net caloric intake will harm you over a one day period. Metabolism does not slow during the first 36-48 hours of a fast although it can slow over longer periods:
http://www.ncbi.nlm.nih.gov/pubmed/2405717
http://www.ncbi.nlm.nih.gov/pubmed/10837292

People who are underweight can be harmed if they consume too little over long periods of time. This is why long term human fasting studies are always done with overweight/obese participants. Long term fasting is not suitable for anyone who is not both healthy and fasting under medical supervision. Fasting for long periods can be dangerous for those with diabetes for example. Under medical supervision such as the study cited below, blood tests are done regularly and electrolytes are monitored.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2495396/

Every person on the planet has a negative net caloric intake over some period of time. If you walk around the block, unless you are eating during the walk itself your net caloric intake during that walk was negative after subtracting the calories you burned by walking. Every person fasts. We just fast for different periods. If you eat at midnight before falling asleep and then eat again at 8am when you wake up, you just fasted for 8 hours. We all burn calories while we sleep.

Do you really think there is something magical about a 24 hour period that causes you to "starve" if you do not eat? There is little difference between a 23 hour fast and a 25 hour fast except for perception. Lots of people fast for 19 hours every day and eat all of their food in a 5 hour window (19/5). Others fast for 16 hours and eat for 8 (16/8). Other people fast 2 days out of every week (5:2). It's called intermittent fasting. Perhaps your questions would be better answered in the MFP intermittent fasting group.
http://www.myfitnesspal.com/groups/home/49-intermittent-fasting

Here is some information to get you started:
http://www.leangains.com/2010/10/top-ten-fasting-myths-debunked.html
Edited by MinimalistShoeAddict On April 5, 2013 10:51 AM
  26529664
April 5, 2013 10:46 AM
Awesome info minimalist...
thanks for taking the time to share..
I also see that each of your statements is well quoted... may it influence all those who will promptly dispute you without any knowledge other than that which "the ripped guy at the gym" offered them.
Edited by betoarango On April 5, 2013 10:49 AM
  30326427
April 5, 2013 4:23 PM
I hate to burst the bubble on providing literature to support your point. I am a pharmacist and I spend my life evaluating literature. The literature you provided doesn't actually support your point. The first two studies were short term (48-84 hours) fasts. This is much different than the typical person on MFP who eat far below their daily needs for months at a time. They note an increase in thermogenesis in their study. Something I don't dispute. I personally practice a 16/8ish (give or take) intermittent fasting way of eating. The first study the enhanced thermogenesis only amounts to about 70 additional calories per day. The second comes out to a significant 300ish calories. Their fairly short periods of decreased intake is still not the same practice as eating below your caloric needs for long periods of time. Your last reference on the patient who fasted for nearly a year also may not apply. The study subject was over 400 lbs. Many of the people I see here worrying about eating below their BMR are not that obese. And while they found no adverse effects in their study (during which the patient was supplemented with vitamins and electrolytes) they note several case studies where the study subject died during the prolonged fast. That is hard to ignore. I do support evidence based practice, but it is important to understand that often times literature may not generalize to the population you are studying and it is also important to read and understand the full paper. This does not mean that I don't support short fasts, but that is far different than months of eating far below your energy requirement without the fat stores to support the energy demands of your body.
April 5, 2013 5:29 PM
You are not bursting my bubble. I specified that first two studies related to short term changes in metabolic effect. The topic of this thread relates to a net negative day (24 hours). I tried to remain balanced my acknowledging the contrast in metabolic changes seen over short term vs long terms fasts.

This study in particular is interesting because it studies healthy lean subjects fasting for short periods:
http://www.ncbi.nlm.nih.gov/pubmed/10837292

I cannot cite a long term fasting study with lean subjects because I doubt one exists. I agree with you about that being very dangerous and inappropriate. Since the OP asked about one "net negative day" I tried to focus my response on the impacts of short term fasting (not long term).

I have made no claims about the impact low calorie diets over long periods of time. In fact I clearly stated that long term fasts are not something that should be done unless healthy and under close medical supervision. Perhaps the third study with the 382 day fast was not appropriate for this thread because of its long duration not being relevant to the "net negative day" the OP is asking about. I only included it because it also studies changes in metabolism over time. I also noted the difference in obese people and those who weigh much less and that all long term fasting studies are done with participants with a lot of weight to lose for obvious reasons. Underweight people would suffer serious consequences from fasting for long periods.

My only purpose was to dispel the myth that short term fasts (such as the one day net negative period mentioned by the OP in this thread) are automatically harmful to our metabolism. We are in agreement.

There are many people on MFP who believe that "starvation mode" will kick in if they consume under 1200 calories for one day. I am sure you and I can agree that there is a big difference in one "net negative day" as the OP is asking about and under eating for many days in a row.

QUOTE:

I hate to burst the bubble on providing literature to support your point. I am a pharmacist and I spend my life evaluating literature. The literature you provided doesn't actually support your point. The first two studies were short term (48-84 hours) fasts. This is much different than the typical person on MFP who eat far below their daily needs for months at a time. They note an increase in thermogenesis in their study. Something I don't dispute. I personally practice a 16/8ish (give or take) intermittent fasting way of eating. The first study the enhanced thermogenesis only amounts to about 70 additional calories per day. The second comes out to a significant 300ish calories. Their fairly short periods of decreased intake is still not the same practice as eating below your caloric needs for long periods of time. Your last reference on the patient who fasted for nearly a year also may not apply. The study subject was over 400 lbs. Many of the people I see here worrying about eating below their BMR are not that obese. And while they found no adverse effects in their study (during which the patient was supplemented with vitamins and electrolytes) they note several case studies where the study subject died during the prolonged fast. That is hard to ignore. I do support evidence based practice, but it is important to understand that often times literature may not generalize to the population you are studying and it is also important to read and understand the full paper. This does not mean that I don't support short fasts, but that is far different than months of eating far below your energy requirement without the fat stores to support the energy demands of your body.
Edited by MinimalistShoeAddict On April 5, 2013 6:21 PM
  26529664
April 5, 2013 5:39 PM
Love the debate, Excellent information on previous two posts. Please continue to contribute.
April 5, 2013 5:56 PM
I do three - five to seven hour races through the year. I usually have negative nets on those days, with intakes around 3500 cals.
  28493399
April 5, 2013 8:41 PM
QUOTE:

Has anyone had a negative net calorie intake day. I would like to hear about it.


Why?

QUOTE:

Yes I have them all of the time. I work out three times a day averaging burning 550 each time. In take in 1500 calories per day. I am trying to figure out if that is harmful or not.


You're trying to figure out if burning more calories than your body needs to survive on a regular basis is harmful?

QUOTE:

Every person on the planet has a negative net caloric intake over some period of time. If you walk around the block, unless you are eating during the walk itself your net caloric intake during that walk was negative after subtracting the calories you burned by walking. Every person fasts. We just fast for different periods. If you eat at midnight before falling asleep and then eat again at 8am when you wake up, you just fasted for 8 hours. We all burn calories while we sleep.



Are you seriously using a walk around the block and not eating during the walk as an example?

Am I being trolled?
Edited by DavPul On April 5, 2013 8:42 PM
April 5, 2013 9:00 PM
QUOTE:

Has anyone had a negative net calorie intake day. I would like to hear about it.


This entire week, I've had an issue with *several* negative net calorie intake days. I'm talking -500 calories. It's frustrating. I know that my body needs the fuel, and I just can't seem to get it in me (with GOOD calories--give me junk food and it's DONE) between my 3 meals and a couple of snacks, when I'm burning upward of 600 at the gym every morning. I'm sure I need to eat more at breakfast, but I'm not a big fan of it... I know, I know... breakfast is the "most important meal of the day." I know. :p I have to say, not having enough calories leaves me *exhausted*. Negative a couple hundred isn't so bad, but 500 (and almost 800 today) is really bad. And I still consumed about 1500 calories, and I'm not hungry. I actually had to force myself to eat some popcorn to get my calories up a little more.
  40839557
April 5, 2013 9:05 PM
Yes.
All of the time.
I don't eat when I'm full.
In my charts I put in the goal to lose 2 lbs/week the highest that the app would allow and it gave me 2,030 calories to eat.
There's no way I could physically eat that much.
I function just fine eating 1,200-1,300 calories.
(Even eating that much I still lose tons of weight. I'm eating the right foods.)
Once I get to the lowest I can go where I look good might bump it up to 1,400-1,500 calories when I start to bulk up a little bit on muscle.
At this point I'm just sculpting to see where I'm at then build upon it.
Like a blank canvas essentially.
April 5, 2013 9:21 PM
QUOTE:

Yes.
All of the time.
I don't eat when I'm full.
In my charts I put in the goal to lose 2 lbs/week the highest that the app would allow and it gave me 2,030 calories to eat.
There's no way I could physically eat that much.
I function just fine eating 1,200-1,300 calories.
(Even eating that much I still lose tons of lean muscle mass. I'm eating much too little food.)
Once I get to the lowest I can go where I look good might bump it up to 1,400-1,500 calories when I start to bulk up a little bit on muscle.
At this point I'm just sculpting to see where I'm at then build upon it.
Like a blank canvas essentially.


Fixed your post.

1300 for a male that's more than 4 and a half feet tall is crazy time. I remember when I first started on MFP a year ago and set the app to lose 2 pounds per week. It game me 2050 cals per day. Know why? Because I weighed 276 pounds. So if you're getting the same number I did, I'm going to go out on a limb and assume your are taller than 4.5 feet and weigh more than 125 pounds.

Not to ruin the whole thing for you, but there's no bulking up at 1400 calories for a grown man. No sculpting either. Eat more. You're hurting yourself this way. Dead serious.
Edited by DavPul On April 5, 2013 9:22 PM
April 6, 2013 10:53 AM
Not here to argue but I've seen several articles on IF, just something to think about. :)

http://www.dangerouslyhardcore.com/1299/intermittent-fasting-part-2-the-fights-over/
QUOTE:

I like the idea of Intermittent Fasting, I’m just not keen on the results. It is easy to not eat all day then blast through a few thousand calories before hitting the sack (or burning the midnight oil in my case). I can say it definitely causes weight loss (at least this particular protocol)—the problem is what kind of tissue the lost weight comes from.

I’ve even used a modified version of The Warrior Diet* with aesthetic oriented athletes (like figure competitors and bodybuilders) during the last week of contest prep allowing them to eat hamburgers and French fries, pizza and fried chicken while still walking on stage shredded. For short bursts, it seems to work—whatever work means in this context.

(*Don’t take my comment here to mean I used The Modified Warrior Diet, which seems to have no place in performance nutrition.)
So, when my life turned into a maelstrom of work, when finding time to breathe, let alone eat seemed difficult, I thought I’d test IF (keep in mind this was not a formal test of all conceivable IF protocols, I simply needed to save time and from what I had read about IF, it seemed a plausible way to do so and preserve my body composition).

When I started, I trained only one or two days a week due to time constraints. I had been using Carb Back-Loading adjusted to my training schedule to maintain my weight and strength. I was at 220 lbs (100 kg) and had 6% body fat as tested by water tank. (This is the range—6 to 7% body fat—that myself and non-competitive clients hold comfortably year round with Carb Back-Loading; getting to that point sometimes requires a prior application of Carb Nite.)

The first week went pretty well, I felt good, my skin tightened slightly and no aspect of the diet was a challenge. I’d wake, have coffee—sans any nutritive additives like cream—and run the rest of the day without food and without hunger (due mostly to the hunger-control produced by long-term adherence to an ultra-low carb diet). At about 7 in the evening, I re-fed like nobody’s business (gluttony would be an understatement). My workouts (I could still only get one to two sessions per week) felt great.
Fast-forward to week 6. I knew I had to stop. For as convenient as it was and as easy, my body did not cope well. People kept telling me I looked “small”, not bad, just small. I had dropped over 18 lbs. I was not ripped, not shredded. Try flat and my skin felt loose. Actually, despite a quick enhancement of my 6 pack the first week, my abs, which I’d become quite fond of over the last year, disappeared. I looked like crap. My strength decreased with each workout after the first week. I was more than displeased.
Now, I admit that I’m an extreme case. I used to carry 20+% body fat but now my walking weight is 220 with a body fat percentage of six. At those numbers, I didn’t even have 18 lbs of fat left on my body when starting the IF experiment. I clearly lost lean mass during my IF trial.

At these extremes, however, we can evaluate the claims of dieting strategies, especially those purporting to produce lean gains or a decrease in body fat without losing muscle. I know my training schedule was not optimal, but with that same schedule (using a Shockwave program) I maintained my muscle mass and strength for over two months. The only thing I changed for the ad hoc IF experiment was my diet.

This transformation (more like a degradation) not only ignited my ire, it sparked curiosity into why IF didn’t preserve my muscle mass as promised, despite the supposed massive increase in GH. If there’s anything I hate more than losing muscle mass, it’s a question without an answer.

Being muscular and defined is a war between breakdown and synthesis and for those drafted to the cause, the battle ensues from morning to night. Being jacked depends on shifting all forces toward growth and defending against destruction (as does, arguably, every facet of health). It turns out that IF is the Axis of Evil in this battle by shutting down synthesis and letting catabolic processes run wild like Lindsay Lohan on coke.

The body is not kind to muscle mass when fasting. Fasting rapidly adjusts several regulators of growth many of which act to shutdown the mTOR pathway**, one of the most critical pathways known for protein synthesis and protection against protein breakdown[1]. The cascade of suppression signals starts quickly, within 12 hours of fasting[2,3].
(**Although the details are complex, the shutdown is mediated by several factors critical to mTOR’s function, such as SIRT1 gene regulation, levels of which rise during fasting and negatively regulate mTOR[4,5] and AKT, which decreases in activity during fasting, thus down-regulating the mTOR channel[6-8]. )

Don’t downplay the importance of the mTOR shutdown. Inhibiting the mTOR pathway prevents resistance training from triggering muscle growth when mTOR is deactivated[9]. Not only can you not build muscle, but the same changes that prevent the activation of mTOR also prevent insulin from stopping the breakdown of muscle[10-11] (this is directly attributed to the decreased AKT activity mentioned above).

Also contributing to the anti-anabolic milieu is the fact that although GH concentrations increase, free IGF-1 levels decrease[12-13]. Although GH goes up, only its fat burning properties persist and it’s muscle building properties disappear. This decrease in free IGF1 suppresses the mTOR pathway even further[14]. By practicing IF, you get greater GH release but ablated anabolic response.

Eh, anti-anabolic? What do you care? Maybe you don’t care that you won’t grow. Maybe you don’t train for size, but you do train for performance and to perform, whatever muscle you do have is critical and probably hard-earned. You might care, then, that mTOR activation protects against the destructive effects of cortisol[15]. Shutting down mTOR (and all the changes that accompany this[16,17]) allow the catabolic steroids—glucocorticoids—to chew up muscle tissue.
(A full understanding of all the transcriptional, hormonal and nutrient regulators of growth is beyond the reach of science at the moment and definitely beyond the scope of this article, but here’s an interesting paper on the complexities involved: Regulation of skeletal muscle growth.)

Granted, my results constitute an observational case study. One subject, no hard data except a scale and definite visual, visceral and performance related changes, none of which I can classify as good. And the reactions caused by IF seem so esoteric and sciency, do they really contradict all the good research done directly on the transformative and performance enhancing properties of Intermittent Fasting? Because as emphatic as many of the proponents are, a decent body of research must exist.

But after two weeks of digging through research, reading, tracing through citations of other papers, all I found to test the power of IF was a single study done on humans. One. It describes the results of an every-other-day fasting schedule on body composition. Two things emerged from this study: 1) over the long term, there was no difference in total lipid, protein or carb utilization compared with a standard diet; and 2) the study showed that IF decreases metabolism over time[18].
Other studies on Ramadan fasting, even ones that control and match calorie intact between experimental groups demonstrate the same result[19,20]. It’s safe to say, that for fasts of 14 to 36 hours, there is no benefit, only cost.

(Oh yeah, did I mention that in animal models, IF also amplifies white-fat cells ability to store fat and shift nutrient partitioning toward body fat instead of energy use[21]? This alone could explain the drop in metabolism seen in the single human study: as the body pushes more calories into fat for storage, metabolism drops to accommodate the redirection of energy.)
These results explain what happened to me and why I was unable to maintain my physique and performance. Most people wouldn’t notice the deleterious side of IF because they start at such high levels of body fat that can mask—literally and figuratively—muscle loss and help maintain strength for a time.

But I’m interested in high-performance, not different ways to achieve average. I’m not happy with anti-anabolic protocols that allow catabolic reactions to run rampant. For the average person who doesn’t want to train, the anti-anabolic effect may prevent the formation of new fat cells along with preventing muscle growth. But for those of us who train heavy (even at just twice a week, I still trained heavy), each training session is severely catabolic.

Remember: muscle growth is the balance between the muscle protein breakdown (catabolic process) that occurs from training and muscle protein synthesis (anabolic process) ignited after training and for the next 24 to 48 hours or so. If you shut down the anabolic pathways, or impair them, you give favor to the destruction. And if you can’t stop the breakdown anymore, then you’re really screwed. IF does both. No more PRs, no more capped delts, no sexy abs—it’s all going to go.
(I should also mention the fact that fasting clearly decreases anaerobic performance[22] and power-production[23], two key elements of resistance training.)

The missing ingredient in intermittent fasting, or the overlooked piece of information, is that the body responds to both nutrient restriction and carbohydrate restriction and takes different actions with the two. The body is highly sensitive to nutrient availability and energy balance. Take away energy (all food) or over-tax the system, and anabolic processes shutdown and catabolic processes start up***.

(***Energy flux sensitivity can be instantaneous, as well, through activation of AMP-kinase[24-27] which also shuts off muscle growth via-mTOR down-regulation[28-30]. This is one reason that over-exhaustive exercise methods like CrossFit, Insanity Workouts and P90X stop muscle growth and repair and decrease performance.)
Take carbs out of the diet and reintroduce them at the correct time and you get all of the benefits of Intermittent Fasting. Take all food out of the diet and re-feed, and suddenly, you add in a batch of anti-anabolic, catabolic effects. As I showed in Part 1, carbs are the drug here, not simply food.

My training hasn’t changed, but I re-embraced the magic of Carb Back-Loading, even though it requires more planning and time. My size is coming back—back to 215, up from 202—and my abs are back thanks to a crazy new supplement called food. I started eating again, but according to Carb Back Loading, which imparts all the benefits and none of the downside of IF (abstaining from food completely seems to destroy all but the massive thermic effect of food—excess body heat—during the re-feed[31-33]).

Your first fast-breaking nutrition should prolong fat burning, trigger muscle growth and repair and provide the raw material to do so (but not a huge bolus) [34], and doesn’t need to be much, but something. I designed the A.M. Accelerator Shake with this in mind. You shouldn’t completely fast longer than 12 hours, ever. So, if you stop eating 2 hours before bed, sleep 8 hours, you should probably eat within 2 to 3 hours of waking. If you eat right before bed, sleep 6 hours then you can probably wait 5 or 6 hours before eating after you wake.

Like I said, Carb Back-Loading is Intermittent Fasting evolved.

In Part 3, I’ll cover the health benefits of IF and how to achieve them without IF and Part 4 (the finale) will be a distilled list of what IF can do, what the science says and when using IF is a good idea (or, at least, not such a bad idea).
Note: There are still times when I recommend going longer than 12 hours without food, but those are special situations, normally during contest preparation for a very short stint (maybe a single 20 hour fast) at a very particular time (three or four days before getting on stage), but even in these sans-food periods, I do have clients ingest small amounts of fat in one form or another—usually heavy whipping cream, coconut oil or a combination thereof with coffee.
Intermittent Fasting should be seen as a tool, not the entire toolbox.
April 6, 2013 10:57 AM
There are several links that are more involved here -
http://www.longecity.org/forum/topic/47354-mess-up-your-heart-with-intermittent-fasting/page__p__473475#entry473475
Edited by etoiles_argentees On April 6, 2013 10:58 AM
April 6, 2013 11:01 AM
No.... welll actually yes maybe once... but only because I've walked (non-strenuously) for about 4 hours that day (say walking around the beach or something) and burned over 1500 calories.. and I've only eaten 1500 calories that day. It is not something I intend to make a habit of. I want to lose weight more than the next person, but I am very aware this is not a healthy way to do it, especially on a regular basis. If it's once a week, maybe not too bad, as long as you are actually eating at least 1200 calories. But I've read fasting can cause havoc with your metabolism and heart condition.

I try to aim my net at least 1200... but 1500 is better... and I still manage to burn over 2000 calories every week, often 3500.
Edited by rheelizabeth On April 6, 2013 11:03 AM
  8001526
April 6, 2013 11:11 AM
QUOTE:

There are several links that are more involved here -
http://www.longecity.org/forum/topic/47354-mess-up-your-heart-with-intermittent-fasting/page__p__473475#entry473475


First of all, those are rats.

That was from ADA or EOD fasting.

Not all IF is ADA. I think most people here use IF to mean 16/8 or 18/6..not alternate day fasting.

.
Edited by cmriverside On April 6, 2013 11:15 AM
  5978
April 6, 2013 11:21 AM
I have negative net calories all the time! I eat 1200-1300 of veggies and protein and burn usuallly 1700 calories! I feel fine and since I have a lot of weight ot loss its okay or so I been told. I also am not hungry so why eat more!
  33328817
April 6, 2013 12:18 PM
Okay, but there is so much more to look at.

QUOTE:
Plasma agouti-related protein level: a possible correlation with fasted and fed states in humans and rats.
Shen CP, Wu KK, Shearman LP, Camacho R, Tota MR, Fong TM, Van der Ploeg LH.
Source
Department of Obesity and Metabolic Research, Merck Research Laboratories, Rahway, NJ 07065, USA. chunpyn_shen@merck.com

Abstract
We measured plasma concentrations of agouti-related protein (AGRP) in humans and rats and determined whether these were affected by ingestion of a meal after fasting. In 17 healthy human subjects, the mean plasma concentration of AGRP was lower in the fed state than in the fasted state. Two hours after a breakfast meal, AGRP levels dropped by 39%. By contrast, a continued fast for 2 h increased the average AGRP concentration by 73%. In rats with diet-induced obesity, refeeding resulted in a 50% decrease in plasma AGRP concentrations following a fasting-refeeding protocol. Our results support the notion that plasma AGRP may serve as a biomarker for the transition from a fasted to the satiated state.



QUOTE:
Plasma concentrations of alpha-MSH, AgRP and leptin in lean and obese men and their relationship to differing states of energy balance perturbation.

Hoggard N, Johnstone AM, Faber P, Gibney ER, Elia M, Lobley G, Rayner V, Horgan G, Hunter L, Bashir S, Stubbs RJ.
Source
Rowett Research Institute, Aberdeen, UK. nh@rowett.ac.uk
Abstract

OBJECTIVE:
A great deal of attention has focused on the central role of alpha melanocyte-stimulating hormone (alpha-MSH) and its antagonism at the melanocortin-4 receptor (MC4R) by agouti related protein (AgRP) in the regulation of energy balance. However, very little is known regarding the function of circulating AgRP and alpha-MSH in humans. We aimed to determine whether circulating alpha-MSH and AgRP are responsive to long-term perturbations in energy balance, in a manner consistent with their central putative functions.

DESIGN AND MEASUREMENTS:
Circulating alpha-MSH, AgRP and leptin were measured in both lean (n = 11) and obese (n = 18) male volunteers, some of whom (lean n = 11, obese n = 12) were then allocated one of two weight-loss dietary strategies to achieve about 5% weight loss. This was achieved by either total starvation (for 4-6 days) for rapid weight loss or a very low calorie diet (VLCD, 2.6 MJ/day) (11-12 days) for less rapid weight loss, in both the lean and obese volunteers.

RESULTS:
At baseline, prior to any weight loss both plasma alpha-MSH (15.8 +/- 1.2 vs. 5.8 +/- 1.0 pmol/l +/- SEM; P < 0.001) and AgRP (49.4 +/- 2.4 vs. 10.1 +/- 0.9 pg/ml +/- SEM; P < 0.001) were elevated in obese subjects compared with lean. In both cases this correlated closely with fat mass (P < 0.001), percentage body fat (P < 0.001) and leptin (P < 0.05). Plasma AgRP increased significantly during a 6-day fast in lean individuals (11.1 +/- 1.6 vs. 21.6 +/- 3.1 pg/ml +/- SEM; P < 0.05) but not in the VLCD subjects or in the obese, while alpha-MSH was not affected by any changes in energy balance in either the lean or the obese volunteers.

CONCLUSION:
We show a difference in alpha-MSH and AgRP in lean and obese subjects that correlates closely with body fat at baseline. We demonstrate an increase in plasma AgRP during a 6-day fast in lean individuals that is coincident with a decrease in plasma leptin. This increase in AgRP was not due to weight loss per se as there was no change in AgRP as a result of the same weight loss in the VLCD intervention in lean individuals. The source of the increase in plasma AgRP and its physiological function in the periphery remains to be elucidated but we suggest that the dynamics of the change in plasma leptin may determine the elevation in fasting plasma AgRP in lean subjects.
April 6, 2013 12:23 PM
So, leptin is affected. Yeah.


How does that have anything to do with heart damage in rats?


Sorry, OP. E_A, maybe you should post this stuff in a new thread. It really has nothing to do with his question.
  5978
April 6, 2013 12:36 PM
You're right, I would just rather have people think than tell them what to think.
It's just something I was on elsewhere, this isn't the place for it.
April 6, 2013 12:54 PM
On my long run days I usually burn 2,000 + calories and I'm always negative net; however, I do my carb loading the day before and try to eat anywhere between 500-1,500 extra calories then . . . It all works out for me.
  8476101

Reply

Message Boards » Fitness and Exercise

Posts by members, moderators and admins should not be considered medical advice and no guarantee is made against accuracy.