why do ppl do low carb for weight loss?

but a lot of people dont eat low carb and arent overweight?
so then why would carbs make some humans fat but not all of them?
just had this thought today at work
corworker is doing a low carb diet to lose weight
and there i was shoveling rice in my mouth and just shrugging. works for me.

Replies

jgollnick

For me, I choose to do slow carb. The carbs that I do eat have a lot of fiber. So I still eat bread, just whole wheat. I will eat sweet potatoes over regular potatoes because of the fiber content. Fiber one cereal, lots of beans, and high fiber pasta, and vegetables. I have hard time getting away from whit rice but I try to keep it to a minimum. The only sugar I eat is from fruit and vegetables. The idea is to not use energy produced by carb intake but insteead use my stored energy (Fat). So far I lost 51 lbs. of it.

Created by MyFitnessPal.com - Free Calorie Counter

Blizaine

I think a lot of people don't fully realize the benefits of going low carb or the health risks with eating refined sugars and grains. I was the same way for pretty much my entire life, until I did some research. Now I still eat tons of non-starchy veggies and some fruit because it has a low glycemic index and doesn't elevate sugar levels like breads, rice, pasta, sugar, etc..

The reasons I do high fat (160g+ a day) and low carb (sub 25g net carbs a day).

1) Your body does not need carbs in any way shape or form.
2) Fats are healthy (and yummy)
3) It reverses, corrects and prevents diabetes, metabolic syndrome, etc.
4) it can prevent Heart Disease
5) it improves cholesterol
5) It can treat and prevent Alzheimer's (aka, Type 3 Diabetes. where brain becomes insulin/glucose resistant)
6) prevents or slows Cancer and tumor growth. cancer loves glucose, can't use ketones.
7) more energy during the day
8) steady energy all day (no energy swings or post lunch afternoon sluggishness)
9) neuronal stabilization and better mental focus all day long
10) brain is more efficient on ketones than glucose
11) ketones prevent epileptic seizures, and migraines
12) you burn fat as fuel 24 hours a day while in ketosis (umm, awesome?)
13) fat is more satiating
14) preserves LBM
15) blunts appetite

But to each his own. It might not be for everyone. If you are an ectomorph and have trouble gaining weight, then maybe you don't need to go to this extreme. But if you feel like metabolic calculators that tell you to eat X calories and you will loose X weight (like on MFP every-time you submit your daily food log) and they are never right for you. Chances are your body is partitioning the carbs you eat into your fat at a higher rate than someone who can eat tons of food and never get fat. So why not eat low carb? might be a better question.

LAW_714

I'll have to do some digging around and see if I can find the info, but there's a study that's discussed in depth in the book Rethinking Thin, where two groups were put on Atkins vs the low calorie diet that's done at university weight loss clinics. The book was published before the study was completed. However, I read the follow up for the study in an article and the low carb group actually did have a very slight better success rate-still an overall failure, like those in the low calorie group, but some of the low carbers were able to stick with it long term vs. almost no one sticking to the low calorie diet. Off to do some googling to see if I can find the article!

If it's the study I think you're referring to, then it showed that participants on all the different diets ended up deviating towards the median in the long term (the low-fat/Ornish folks added fat back to the diet by 6 months. The low carbers upped their carbs by 6 months. That sort of thing. When the data was analyzed in depth, the only real statistical difference was that the people with insulin resistance were slightly more successful on low carb diets.)

Video of analysis of the study discussing the results at Stanford University's medical school

http://youtu.be/eREuZEdMAVo?t=39m27s

rachelwarner32

My husband did Mark Sisson's Primal Blueprint and lost 45 and has kept it off for almost 2 years. Although he was very strict during the initial weight loss he now eats chips,cookies,drinks beer and doesn't gain weight. Obviously he doesn't eat them every day but he's proven that cutting carbs equals sustainable weightloss. I've recently got on board and have lost 12 pounds in 2 weeks and my energy is better than when I was eating unhealthy carbs. The hunter/gatherer diet works for us because we're willing to put in the effort to make it work. Not everyone can give up carbs though.

mwooderson

I know that for me it's not the amount of carbs but the type of carbs. If I eat veggies - those come with fiber, they fill me up, and I feel great. If I eat bread, on the other hand, or sugary sweets - I get a sugar rush, then a crash and I want more, more, more and it's very difficult for me to control how much I eat. And obviously healthy fats and proteins are good for you too, so I have plenty of room for those foods as well if I'm not overdoing carbs.

I still end up with something like 100g of carbs a day, but also like 60+g of fiber, so I don't get the sugar rushes, and don't feel hungry and it's easy to for me to maintain. I don't really have to weigh things like that - I'm not going to overeat raw green beans or whatever to the point where I gain weight, so I can estimate and it comes out close enough. When I was eating starchy carbs, I'd really have to strictly watch portion sizes to keep it under control and felt hungry all the time.

I realize not everyone suffers from the same cravings and such. So if you can eat those things in moderation without a struggle, I wouldn't sweat it. If you're constantly craving more, it might be worth looking into reducing sugary/starchy carbs to see if it makes things easier for you. Sounds like you don't need to worry about it, but maybe the above helps make it make sense why some people do.

Through trial, error and successes, I do best steering clear of breads, pasta and starchy veggies as well. My daily carb intake usually ends up somewhere between 80 to 100g's per day. It works for me and also keeps me from having to measure and weight meticulously. It's really really difficult to overeat raw broccoli.

astartig

Not sure. Wondered this myself. I love carbs. All of them. Plus, when I tried out Atkins (back-in-the-day) I was so lethargic and yucky feeling that I couldn't stick to it for long. I find it easier to watch my caloric intake and be active. It works better for me!

This is a well known phenomenon known as "carb flu" or "induction flu". While your body is becoming fat-adapted you may not feel as good for a week or two, but if you stick it out you will feel a-m-a-z-i-n-g after that. Also for those doing induction you need to make sure to eat plenty of sodium (3-5 g/day), that will help prevent a lot of the yucky feelings. A couple of cups of salty broth added to your food intake would have done wonders.

Most of my adult life I've tried to avoid salt because I retain water SO easily. eat out gain 10 pounds by morning. no kidding. but I've been trying to make a point of adding reduced sodium salt to stuff for the potassium and iodine.

Have you looked into the amount of potassium you can get from natural foods without having to resort to eating salty stuff? I did this recently and was pretty surprised. The daily recommended for most people is about 3500mg/ day and you can get 925mg from a baked potato with skin on, 425mg from a banana, 290mg from a tomato, etc. I also have water retention and sodium issues and I was really excited to realize that I do not need to eat a ton of salty stuff in order to get plenty of potassium.

http://www.drugs.com/cg/potassium-content-of-foods-list.html

Why would you need added salt if you're not on a low carb/high protein diet?

I avoid all salt when I am not on a low carb diet because i retain water too badly. I do get some just from regular sources then, you only need the salt in the diet and added potass when you're on a diet like this.. .

astartig

They think it's a quick way to lose weight, when really, as soon as you touch carbs again, you will probably blow up like a balloon

True; but the same with any diet - as soon as you revert to your old ways, the weight piles on with a vengeance. Low fat/low calorie is no exception.

I guess what I meant to say is there is no longevity in a low carb diet.

There's a 95% failure rate for long term weight loss success, regardless of what plan you follow. Only 5% of us will actually keep the weight off for more than five years-regardless if we follow a lower carb or lower calorie diet for weight loss and maintenance. I don't do a low carb plan (I don't really track anything), but low carb is no better or worse than a low calorie diet and for some people it does work better for them, and they can do it long term.

A great book to read, for more info on the studies that have been done, is Rethinking Thin, By Gina Kolata. One of the best books I've read about the realities of dieting/losing weight.

Studies schmudies.. as far as success rates go. Why are the people in studies on diets? Cause they get paid by the people doing the study to go on that diet. they're poor people generally who are getting paid. They aren't doing it because they have the drive.

It's also a small select group. there is no way to know the actual numbers of dieters in the wild. Regardless it doesn't matter how many fail or succeed on any particular diet because they aren't YOU.

the real issue isn't the diet, it's the dedication. if you go on a diet thinking you can go back to doing what you were doing before it just isn't going to work regardless of the diet. if you honestly are looking at it as a lifestyle change that's a different story. Citing studies for this kind of thing is just pointless.

you're dooming yourself to failure if you only go by rhetoric.

JisatsuHoshi

the real issue isn't the diet, it's the dedication. if you go on a diet thinking you can go back to doing what you were doing before it just isn't going to work regardless of the diet. if you honestly are looking at it as a lifestyle change that's a different story. Citing studies for this kind of thing is just pointless.

^ This

wamydia

Not sure. Wondered this myself. I love carbs. All of them. Plus, when I tried out Atkins (back-in-the-day) I was so lethargic and yucky feeling that I couldn't stick to it for long. I find it easier to watch my caloric intake and be active. It works better for me!

This is a well known phenomenon known as "carb flu" or "induction flu". While your body is becoming fat-adapted you may not feel as good for a week or two, but if you stick it out you will feel a-m-a-z-i-n-g after that. Also for those doing induction you need to make sure to eat plenty of sodium (3-5 g/day), that will help prevent a lot of the yucky feelings. A couple of cups of salty broth added to your food intake would have done wonders.

Most of my adult life I've tried to avoid salt because I retain water SO easily. eat out gain 10 pounds by morning. no kidding. but I've been trying to make a point of adding reduced sodium salt to stuff for the potassium and iodine.

Have you looked into the amount of potassium you can get from natural foods without having to resort to eating salty stuff? I did this recently and was pretty surprised. The daily recommended for most people is about 3500mg/ day and you can get 925mg from a baked potato with skin on, 425mg from a banana, 290mg from a tomato, etc. I also have water retention and sodium issues and I was really excited to realize that I do not need to eat a ton of salty stuff in order to get plenty of potassium.

http://www.drugs.com/cg/potassium-content-of-foods-list.html

Why would you need added salt if you're not on a low carb/high protein diet?

I avoid all salt when I am not on a low carb diet because i retain water too badly. I do get some just from regular sources then, you only need the salt in the diet and added potass when you're on a diet like this.. .

Or when you are on a diuretic for a condition like high blood pressure. Low potassium can be a real issue due to the extra water loss. It's also known that people who have problems wtih retaining a lot of water weight can sometimes reduce it by making sure they are getting plenty of potassium while reducing their sodium intake and drinking extra water.

bcattoes

My husband did Mark Sisson's Primal Blueprint and lost 45 and has kept it off for almost 2 years. Although he was very strict during the initial weight loss he now eats chips,cookies,drinks beer and doesn't gain weight. Obviously he doesn't eat them every day but he's proven that cutting carbs equals sustainable weightloss.

I don't think anyone is suggesting that low carb is not sustainable for anyone. Just that most do not sustain it.

But, if your husband now eats a lot of carbs, how did he prove that low carb is sustainable for him? It sounds more like he proved he doens't need to give up carbs to maintain a healthy weight.

bcattoes

I think a lot of people don't fully realize the benefits of going low carb or the health risks with eating refined sugars and grains.

Luckily there is SOOOOO much wiggle room between those 2 extremes.

wamydia

the real issue isn't the diet, it's the dedication. if you go on a diet thinking you can go back to doing what you were doing before it just isn't going to work regardless of the diet. if you honestly are looking at it as a lifestyle change that's a different story. Citing studies for this kind of thing is just pointless.

^ This

I'm pretty sure a lot of the numbers on diet failures are derived from looking at people who have done weight loss programs on their own and how they fared in the long term, not just designed studies like this, so I think the numbers are pretty valid. That said, I agree with you about lifestyle change. One of the best pieces of advice I ever got was "Don't do anything to lose weight that you aren't willing to do for the rest of your life to keep it off."

tomg33

It is simple physiology that a low carb diet would lead to decreased glycogen reserves and anaerobic performance. However it depends on your goals. Obviously not many people are training for maximal strength using compound resistance exercises otherwise they would immediately notice the difference between being carbed up and being low carb (~100 or less).

bcattoes

the real issue isn't the diet, it's the dedication. if you go on a diet thinking you can go back to doing what you were doing before it just isn't going to work regardless of the diet. if you honestly are looking at it as a lifestyle change that's a different story. Citing studies for this kind of thing is just pointless.

^ This

I'm pretty sure a lot of the numbers on diet failures are derived from looking at people who have done weight loss programs on their own and how they fared in the long term, not just designed studies like this, so I think the numbers are pretty valid. That said, I agree with you about lifestyle change. One of the best pieces of advice I ever got was "Don't do anything to lose weight that you aren't willing to do for the rest of your life to keep it off."

Any long term diet study is unlikely to be controlled. It's nearly impossible to find a large enough group of people willing to be sequestered and have their diet strictly controlled for a year or more. It's always done via survey.

LAW_714

It is simple physiology that a low carb diet would lead to decreased glycogen reserves and anaerobic performance. However it depends on your goals. Obviously not many people are training for maximal strength using compound resistance exercises otherwise they would immediately notice the difference between being carbed up and being low carb (~100 or less).

On the other hand, if you have a career where you work in an office at a computer for ten hours a day, have to commute home, cook dinner, clean the kitchen, etc, you may not have the hours a day necessary to deplete glycogen stores resulting from consuming 300g of carbs a day.

Different people have different lifestyles, different bodies, and different needs.

wamydia

the real issue isn't the diet, it's the dedication. if you go on a diet thinking you can go back to doing what you were doing before it just isn't going to work regardless of the diet. if you honestly are looking at it as a lifestyle change that's a different story. Citing studies for this kind of thing is just pointless.

^ This

I'm pretty sure a lot of the numbers on diet failures are derived from looking at people who have done weight loss programs on their own and how they fared in the long term, not just designed studies like this, so I think the numbers are pretty valid. That said, I agree with you about lifestyle change. One of the best pieces of advice I ever got was "Don't do anything to lose weight that you aren't willing to do for the rest of your life to keep it off."

Any long term diet study is unlikely to be controlled. It's nearly impossible to find a large enough group of people willing to be sequestered and have their diet strictly controlled for a year or more. It's always done via survey.

Believe it or not, that is actually kind of my point. The controlled studies can give you a good look at "if we take X number of people and make them do X diet for X days, how much weight do they lose and can they keep it off?" Useful information. Looking at real people in real life gives you the ability to say "if we look at the average person and let them diet at their own discretion, how much weight do they lose and can they keep it off?" Also useful information. I think that both items give us very valid information about how hard it is to be successful on weight loss programs, but looking at average people doing their thing has the advantage of showing us success rates in real life, aka "what will happen when real people try this for real and not because they're being paid to do this for a study." I'm pretty sure that the overall figures of weight loss failure are derived from looking at both types of information and I think that is a good thing.

Scubanana7

Low carb (e.g. under 50g carbs/day) is a huge deviation from standard eating habits. However, being aware of and reducing carb intake is a very easy way to reduce caloric intake.

Ummmmmmm....."standard eating habits" I am thinking of all the documentaries where they cameras zoom in on 'average' Americans big, fat wobbly butts, huge bellies overhanging the belt, severely obese children with TYPE 2 DIABETES and heart issues.....

and I think "standard eating habits" ????

Great post----reminds me what I did to NEED mfp. STANDARD EATING HABITS oh yeah, love this one.

Carnivor0us

Low carb (e.g. under 50g carbs/day) is a huge deviation from standard eating habits. However, being aware of and reducing carb intake is a very easy way to reduce caloric intake.

Ummmmmmm....."standard eating habits" I am thinking of all the documentaries where they cameras zoom in on 'average' Americans big, fat wobbly butts, huge bellies overhanging the belt, severely obese children with TYPE 2 DIABETES and heart issues.....

and I think "standard eating habits" ????

Great post----reminds me what I did to NEED mfp. STANDARD EATING HABITS oh yeah, love this one.

I ate pretty "standard' too and got fat as ****. Maybe I should just go back to that because my 30g carb-a-day diet is such a huge deviation.

TeaBea

For some people "low carb" is bumper sticker weight loss. They don't need to learn anything except, carbs are bad..... really, really bad. These "people" don't want to (or don't think they need to) learn anything about food ..... just carbs are bad..... really, really bad. Just cut out 1 thing .... and all their problems go away.

This was the low fat diet thing back in the day .....when all fats were created equal and ....fats were bad..... really, really bad.

Carnivor0us

For some people "low carb" is bumper sticker weight loss. They don't need to learn anything except, carbs are bad..... really, really bad. These "people" don't want to (or don't think they need to) learn anything about food ..... just carbs are bad..... really, really bad. Just cut out 1 thing .... and all their problems go away.

This was the low fat diet thing back in the day .....when all fats were created equal and ....fats were bad..... really, really bad.

I like how you put quotes around the word 'people' like they're not real or something. That made me laugh.

Hexahedra

This is just in from National Geographic:
http://ngm.nationalgeographic.com/2013/08/sugar/cohen-text

It confirms that the boogeyman is Fructose, also known as fruit sugar. Fructose is in almost every fruit and plant we eat, although obviously the percentage is highest in fruits. When you eat low carb, you automatically eat low Fructose as well as long as you properly count the carb in fruits.

Getting back to low carb:
When you eat at a deficit you WILL lose weight regardless of what you eat. If you eat low carb without maintaining a deficit you will not lose weight, simple as that.

I personally think half of losing weight is a mind game, which is not very different from sports. Because each person has a different personality, the kind of weight loss macros that works for everybody is not identical. You want to stack the deck for you and make it easier mentally to maintain the new lifestyle. Certain carb-rich or sugar-rich foods are binge triggers for many people, so for them low carb diet makes perfect sense. I don't have any trigger food, so I have no need to do low carb to lose weight.

Certain people with certain medical conditions and sensitivities do need to follow a low carb diet. But, for the rest of us trying to lose weight it's calories in vs. calories out.

Now, when you have reached your goal weight and is going on maintenance, or even gaining, then low carb becomes relevant. However, the importance of carb depends on your personal goal. If your goal is mostly to have a lean but muscular look ala a bodybuilder, then low carb is the way to go. If your goal is sports performance or maximum fitness, then you can't do really low carb, not strictly throughout the day anyway.

I'm not saying you can't physically perform without carb, your body can function just fine without it. But, carbs and their sugar derivatives are the most efficient sources of energy your body can have. This means not having carb is not going to make you weak, it's just not gonna make you realize your full potential endurance and strength.

MsEndomorph

back to low carb:
When you eat at a deficit you WILL lose weight regardless of what you eat. If you eat low carb without maintaining a deficit you will not lose weight, simple as that.

Have you done a low carb diet AND tracked your calorie count at the same time? I ask because most people haven't dont both at once...it defeats one of the benefits of going low carb. As is lowering your caloric intake; once again it sort of defeats the appeal of South Beach and the like.

Anyway, I have done both. And in my experience, I can lose weight rapidly on a low carb diet without bothering to eat at a deficit. What I lack in carbs I can quickly and happily make up in fat.

Obviously there are other factors...maybe I feel less sluggish and am more active when I eat fewer carbs. Maybe I'm unknowingly cutting back on my salt, too. I have no clue.

Hexahedra

back to low carb:
When you eat at a deficit you WILL lose weight regardless of what you eat. If you eat low carb without maintaining a deficit you will not lose weight, simple as that.

Have you done a low carb diet AND tracked your calorie count at the same time? I ask because most people haven't dont both at once...it defeats one of the benefits of going low carb. As is lowering your caloric intake; once again it sort of defeats the appeal of South Beach and the like.

Anyway, I have done both. And in my experience, I can lose weight rapidly on a low carb diet without bothering to eat at a deficit. What I lack in carbs I can quickly and happily make up in fat.

A low carb diet does make it easier to lose weight because carb-rich foods are the least filling of them all. Carbs and sugars are efficient energy sources because it only takes a relatively little amount of them to get the same amount of calories, compared to protein and fat.

You can most certainly gain weight doing low carb, it's what bodybuilders do during their bulk phase.

I see your point though. If you do low carb without consciously trying to overfeed yourself, you will generally lose weight, so there's little need to count calories. But, conversely if you're counting calories then there's no need to do low carb (except for medical or psychological reasons).

Fitnin6280

For some people "low carb" is bumper sticker weight loss. They don't need to learn anything except, carbs are bad..... really, really bad. These "people" don't want to (or don't think they need to) learn anything about food ..... just carbs are bad..... really, really bad. Just cut out 1 thing .... and all their problems go away.

This was the low fat diet thing back in the day .....when all fats were created equal and ....fats were bad..... really, really bad.

Just FYI, those of us doing low carb aren't stupid, and most of us have done extensive research to find what works best with our bodies. My doctor reccomended it, and I am pretty sure she isn't stupid either. :noway:

wamydia

Anyway, I have done both. And in my experience, I can lose weight rapidly on a low carb diet without bothering to eat at a deficit. What I lack in carbs I can quickly and happily make up in fat.

Question: If you aren't tracking calories, how do you know whether you are eating a deficit or not?

ironanimal

Anyway, I have done both. And in my experience, I can lose weight rapidly on a low carb diet without bothering to eat at a deficit. What I lack in carbs I can quickly and happily make up in fat.

Question: If you aren't tracking calories, how do you know whether you are eating a deficit or not?

Ding ding ding

mushroomsontoast

I already answered this for you a few pages back, ironanimal ~ my brother lost 7st while eating 3,000 calories plus on a typical day. None of us had ever calculated his calorific intake before, I did it today just out of curiosity & because you'd asked.
Clearly you won't believe anything you are told, you've simply decided it's not possible and so don't believe all the things low carb/keto dieters are saying.
If low calorie/low fat is soooo ingrained upon you that you truly cannot see any other way, then I can understand that you find it hard to believe that calories play no part in a low carb diet; but 3,000 calories a day and *still* losing 7st?
He did try low cal/low fat, but was always hungry and miserable - and who can carry on like that long-term if they've over 100lbs to lose?

I must admit that I never lost as fast as my brother, maybe only half as much, but he was a lot heavier than me.

Maybe understanding the basics of low carb might help - that the body is forced to use FAT as fuel, not carbohydrates....both dietary *and* body fat.

TemikaThompson

I tried eating low carbs with the Atkins diet. It really worked for me as far as loosing fast. The only thing is that I really wanted the other foods that I used to eat like bread, pasta, and sweets. As soon as I started to eat them in proportion I gained all my weight back and then some. I guess whatever balanced diet that a person chooses for themselves, it has to work for "them" and be a lifestyle. It just didn't work for me. After reading this, I am however going to try to limit my intake of carbs because that's when "I" gain weight the most. I do agree with the person that said when you eat them you crave more, but I know for me, I like eating carbs and sweets so I don't think I can give it up completely but I am working towards limiting them in a balance way

mushroomsontoast

Me too Temika, I absolutely mourned potatoes; 'new' potatoes, dripping with butter. Never missed cakes, sweets, chocolate, pasta, rice, none of that...only potatoes. There are low-carb alternatives for a burger bun, cream cake etc, but nothing for the humble potato. And no, cauli mash offers *no* alternative to the little new potatoes I love so much :laugh:

But saying that, we are all here because we ate too much of things we shouldn't. And to undo the damage and get fit there has to be a change and some sacrifice; none of us will ever slim if we carry on eating like we did when we got fat.

Saying that, we'll all get fat again - whatever regime we follow - if we go back to eating like we did.
Low fat, low carb - it has to be a change for life. Yes we can gradually increase our limits when we want to maintain - on low carb it's usually by 10g extra carbs a week until you find your limit - low calorie it may be 100 calories a week, I don't know. But nevertheless it IS for life.

We got fat, so we're sadly *not* one of the lucky people who can eat anything.

Good luck, I really hope your new balance works for you

wamydia

I already answered this for you a few pages back, ironanimal ~ my brother lost 7st while eating 3,000 calories plus on a typical day. None of us had ever calculated his calorific intake before, I did it today just out of curiosity & because you'd asked.
Clearly you won't believe anything you are told, you've simply decided it's not possible and so don't believe all the things low carb/keto dieters are saying.
If low calorie/low fat is soooo ingrained upon you that you truly cannot see any other way, then I can understand that you find it hard to believe that calories play no part in a low carb diet; but 3,000 calories a day and *still* losing 7st?
He did try low cal/low fat, but was always hungry and miserable - and who can carry on like that long-term if they've over 100lbs to lose?

I must admit that I never lost as fast as my brother, maybe only half as much, but he was a lot heavier than me.

Maybe understanding the basics of low carb might help - that the body is forced to use FAT as fuel, not carbohydrates....both dietary *and* body fat.

I'm not ironanimal, so I'm not sure you were talking to me, but I was the one who asked about the calorie deficit this time so I guess I will answer.

The reason I am having a hard time understanding this isn't that I don't understand biochemistry (I'm a Biologist), it's that this argument makes no biological or energetic sense. I buy that eating low carb can help some people lose weight more easily and I will set aside all arguments as to the healthfulness of it. However, there is no reason to believe that a person can literally eat any amount of calories they wish and still lose weight as long as they cut carbs. It simply doesn't matter what the source of the calories is - if you eat more than you use, the excess has to go somewhere. Low carb diets are not magic.

Biologically speaking, a low carb diet that puts a person into ketosis does work differently in that it uses a different pathway (gluconeogenesis) to produce glucose. However, a low carb diet still behaves just like any other diet. Your body won't go to the trouble to break into your fat stores to make energy (by any pathway) until you have run out dietary sources to use. If you are eating enough to meet energy needs, your body doesn't need to get into your fat stores. If you eat more than you need, your body puts it in storage and you gain weight.
http://www.proteinpower.com/drmike/weight-loss/low-carb-and-calories-2/
http://www.huffingtonpost.com/2009/02/25/lowcarb-lowfat-study-find_n_170056.html

The advantage that low carb diets have that make it easier for some to lose weight is that it is energetically more expensive than the traditional carbs --> glucose pathway, so you have to use more of the calories that you take in to create the glucose that you need. That would raise your basic operating costs for the day somewhat (say his BMR would normally be 2500 calories, maybe now it would be more like 3000 -- these are numbers made up as an example, I don't know what they would be exactly), but that isn't a license to eat until you explode. Once you exceed your operating cost for the day, your body has no need to burn body fat and any excess will go into storage.

I think the answer to this mystery is that since food intake, activity level, BMR, and exercise were not tracked while your brother was losing weight, it is likely that your estimates aren't showing the whole picture.