Sugar vs Fat on BBC: Which is Worse?

Sugar or fat, which is worse? That’s the question in the BBC documentary “Sugar vs. Fat” that aired the other night. And it’s been a long time since I got so many e-mails asking me for comments!

It’s an interesting setup. Two identical twin brothers – both of them doctors – go on a diet for a month. One on an extreme low fat diet, one on an extreme low carb diet (not even vegetables are allowed!). Here’s some background information:

MailOnline: One twin gave up sugar, the other gave up fat. Their experiment could change YOUR life

You can watch the show online here if you’re in the UK or watch a lower-quality copy on YouTube if you’re not.

Unfortunately they end up mostly “confirming” their preconceived ideas. Ready? Here comes the spoilers:

Result

Obviously when there is only one person on each diet, chance plays a big role. But I think the findings were more or less what could be expected, it’s mostly the ignorant (or TV-drama) explanations I have objections to.

Weight

First thing first. Even though both brothers were at a fairly decent weight to start with, the low-carb brother lost the most weight: 4 kg (9 pounds) vs only 1 kg (2 pounds) for the low-fat brother.

As study after study show more effective weight loss on a low-carb diet, this should be no surprise. The loss of fat was 1,5 kg on low-carb (a good result in a month) and 0,5 kg on low-fat. Most of the rest was probably fluid. On a very strict low-carb diet you quickly lose a kilo or two of glycogen and water weight.

How much – if any – muscle mass the participants lost is impossible to know as the BodPod test only measures fat mass vs. non-fat mass (including water).

Brain function

For testing the brain function of the brothers the producers chose to make them do stock trading with fake money.

This shows that the producer is ignorant or just interested in a dramatic show. Why? Because short-term stock trading – without insider info or other illegal tricks – is a game of pure chance. It’s been convincingly shown that a trained monkey has a 50% chance of beating a well-educated stock broker. Why? Because it’s all chance.

In other words this test is rubbish, but the low-fat brother wins.

More interesting and relevant is that the low-carb brother complains of feeling “thick-headed”. I’m sure he’s honest. Going on an extreme low-carb diet – without even vegetables – can absolutely result in problems concentrating etc. for a week or even more, before the body and brain adapts to burning fat and ketones.

This problem can often be partially avoided by increasing the intake of fluid and salt. And after a week or two it’s normally gone.

Exercise

For testing their exercise capacity the brothers do “long sessions of uphill cycling”. The low-carb brother predictably loses badly.

Why? Two things: the body needs weeks or sometimes even months to adapt to high-intensity exercise, using mostly fat and ketones. And even then you might need a little bit of carbs for explosive and anaerobic sports like this.

I’ve interviewed Dr Peter Attia who successfully races his bicycle for hours on a very low-carb diet. Even he uses a little bit of slow-release starch for maximum performance on his long training sessions:

YouTube: Very Low Carb Performance

Diabetes

Finally the icing on the (diabetes) cake. The doctor claims that the low-carb brother has become “almost” pre-diabetic by eating low-carb! The word “almost” should actually be interpreted as “not”. I wonder if the doctor knows the first thing about low-carb and diabetes. In fact I wonder how much he knows about diabetes at all.

The low-carb brother has a fasting glucose of 5,1 before the diet (normal) and a fasting glucose of 5,9 after the diet (normal). Did you catch the word “normal” twice? Yes, thats right, a fasting glucose of up to 6,0 mmol/L is considered normal, at least in Sweden. It also varies significantly from day to day. If we tested the doctors’s own fasting blood glucose it might be 5,9 today and 5,1 tomorrow.

The result could be due to chance but sometimes the fasting glucose level actually gets slightly higher on an LCHF diet, while the glucose levels during the day (after meals) is way lower. This is probably because the body is adapted to burning fat and so the need for burning glucose when fasting is lower. Thus you don’t get the same fasting “dip” in sugar levels.

They also did glucose tolerance tests – a much more relevant test. But the result of the low-carb brother is never mentioned. I guess it was normal.

The fact that diabetes is effectively treated with a low-carb diet should tell us everything we need to know. You don’t get type 2 diabetes by eating a diet that can cure diabetes. And you certainly don’t get type 2 diabetes (strongly correlated to obesity) by losing 4 kilos of excess weight in a month.

Summary

The documentary concludes that it’s not about fat or sugar, it’s about avoiding processed food with both fat and sugar in it. I’m sure that strategy would work fine for these two fairly fit brothers. It’s an excellent start. But it’s not enough for everybody.

In people with obesity and diabetes studies convincingly show that low-carb diets are more effective.

Finally, while a super-strict low-carb diet is not necessary for everyone and has possible side-effects (especially during the first week or two) it certainly do not result in diabetes. That’s just ignorant.

What did you think about the documentary?

More

Diabetes – How to Normalize Your Blood Sugar

New Study: A Low-Carb Diet and Intermittent Fasting Beneficial for Diabetics!

Football Champions on a Low-Carb Diet

Swedish Expert Committee: A Low-Carb Diet Most Effective for Weight Loss

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125 Comments

Top Comments

  1. Ken
    Amazing that even the usual media hype over various eating plans is still broadcast like some kind of freakshow tv.
    ive been zero carb (bread, pasta, rice , white potatoes and cereal) for over 5 years (tonnes of veg) and at 40 I have never felt better.
    I play professional paintball with games lasting 7-8 hours without break and do just fine.
    I powerlift as well and since dropping carbs ive got stronger, leaner and faster.
    Ive recomended the paleo way of eating to many friends and clients who have type 2 and all have had fantastic results whih seem to confuse the so called experts. (No surprise)
    Why are they still clinging to the dogma its Ancel Keyes all over again!
    These people need to face facts and embrace a soloution that doesnt require the sale of medications.
    Reply: #3
    Read more →
  2. PhilT
    The low carb twin wasn't keto adapted, the highest blood ketone level written on the flipchart fleetingly visible twice in the cycling segment was 0.5.

    I suspect he ate a ton of protein.

    They should have had a 2 week washout and reversed diets in a crossover protocol, as well as getting advice from low carb experts rather than the carb queen they employed - see her breakfast suggestions at http://www.amandaursell.com/?page_id=988 ( LOL )

    The twin docs have done better in the past http://www.channel4.com/programmes/medicine-men-go-wild/4od#2923146

    Read more →
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All Comments

  1. Allen
    Thank you so much for having the smarts to question many items in this story. I have every other "news" organization fall for this hook-line-and-sinker with no questions whatsoever.

    First, these two, if they even did these diets that they said they did, only did them for a month. They must have worked hard at it too because one lost "2 pounds." Just because of water weight, your weight can change 4 - 5 pounds any day and it means nothing.

    Next, I am on a low-carb diet, and with the possible exception of the first two weeks, I've never had a lack of energy. Just the opposite actually. And my blood sugar certainly hasn't gone up, its gone way down, just like my triglycerides. In fact the only thing going up was my HDL cholesterol.

    Why do news organizations carry such fake stories like this? Its sad, actually.

  2. royal
    To answer your question Allen- WHY DO.....
    Because the world now "runs" on lies, deceit, misinformation and scams- - This "study" is no different. For full info see EDWARD BERNAYS
  3. Mark
    It's rather imporant to know exactly WHAT is involved.
    70g of fructose, galactose or galactan is 0g of glucose
    70g of sucrose or lactose is 36.8g of glucose.
    70g of glucose is 70g of glucose.
    70g of maltose is 73.5g of glucose.
    70g of maltodextrins is somewhere between 73.5g and 77.8g of glucose.
    70g of amylose or amylopectin is 77.8g of glucose.

    Thus 70g of "carbs" dosn't really have much meaning. (Nor does 70g of "sugars" for that matter.)

  4. Mark
    How did the idea that plant fats completly unlike those found in mammals were "healthy" to eat ever get started in the first place?
    Since it's an extraordinary claim where's the extraordinary evidence?
  5. zaranzak
    This is Great articles to read for easiest ways to lose weight ==>
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  6. Matias MOnsalves
    I think these Documentary wast that good, the LCHF was leto adapted? i don't thing so, and also what organism after 10 month with suppression of a macronutrient doest get a overcompensatory response as it was on the glucose tolerance test?...No 24 hour response on these marker.
    Regards..
  7. LIza
    I watched this on demand recently and can only begin to describe my general outrage in the design of this experiment.

    I wrote a rather lengthy email to a colleague who asked me if I'd watche it, and it ran in the same lines as the doc's comments above.

    Personally I find Sam Feltham's self monitored and conducted experiments all the more accurate and well executed.

    BBC, keep trying.

  8. Jonny
    Fresh fruit and veg are the way to go. We're not supposed to eat meat and dairy. Besides weight-loss (BTW you won't be fat if you sustain a fruit and veg diet, fact), you need to consider other factors such as illness - namely diabetes and cancer. Eating a diet high in meat and dairy is being linked to increasing cancer rates.
    Reply: #109
  9. Zepp
    Strange.. becuse its about ones bodys capability to handel glucose!

    But if you have done any new sciens about it, we gonna meet in Stockholm when you get your Nobel prise in medecine!

    Then we can take a coffe and talk about your new sciens!

    Reply: #110
  10. Jonny
    No new science, just nature and common sense and current science.
    If you were designed to eat meat you would lick your lips when you saw a little dog walking by, or when you see road-kill. Also, your teeth and jaw shape would be different and you would likely have claws rather than fingernails! You certainly wouldn't need to cook the meat either, as nature would have given you a gut that could handle the digestion of raw meat!

    Also, name me another animal that consumes the milk of another animal? Surely humans have not been designed in such a way that unless we artificially impregnate a cow, steal its calf, and then hook the cow up to a milking machine all day, we will miss out on vital nutrients!!??

    Stop believing the rubbish that is out there, and start thinking. Simple really, no Nobel Prize required, thanks

    Reply: #111
  11. Zepp
    Well I can only think about cats, dogs, pigs that drink/eat other animals milk!

    But is you aware of the name Mammal?

    It means milk drinkers!

    We are born milk drinkers.. other Mammals too.

    Do you think snakes or sharks have claws.. read your biology book again!

    You do have an odd perspective to biology.

    And I can tell that Homo Sapiens is the only creature that adapted to coocked food.. we are in moste circumstances relayant to that.

    We are omnivores,, if you like it or not,, we can live on a lot of food substances.. and be healty!

    But to day.. its a problem of to much glycemic load thats moste problem.. one have to use them.. there are a shortige of storage facilitys in our body.

    We vill see each other when you get the Nobel prise in Stockholm.. then I would listen to you!

    Reply: #112
  12. Jonny
    Hehe, you are funny. You must have strange mammals where you live! I've never seen a mammal (in natural habitat) drink the milk of another species. Of course mammals drink their mother's milk as babies, but once they can eat solids the nursing ends. I've never seen a pig, cat, dog milk a cow! Cow's milk is designed to provide the nutrients needed by a calf, not an adult human!

    Are you sure we are omnivores? Name me another natural omnivore? Then check the teeth and jaw of your chosen animal. How similar is it to human teeth and jaw?

    Finally, how can a digestive system develop naturally where the food needs artificial preparation? Are you saying that cells have a naturally programmed knowledge of the effects of cooking otherwise inedible food?

    So what is more realistic, the premise that humans were designed to eat only foods which we can naturally digest in its raw state (fruit and vegetable), or that humans were designed to cook to get their natural diet? Sometimes you need to follow logic and look around you.

    Reply: #113
  13. Jenny
    Omnivores: all kinds of pig, all kinds of birds, all but one species of ape/mokey which I don't remeber the name of.
    Dogs and cats (carnivores) are known to sometime chew grass and flowers and berries.
    There are horses (herbavores) that eats baby birds or fish. (https://www.youtube.com/watch?v=DnWso-2YA-E)
    And no the aimals are not forced to eat it

    Point me to one herbavore that has the short digestion of a human. likewise we don't have the very short digeston tracks of carnivores.
    We can be poisoned if we eat the wrong kind of herb/vegetable/fruit. In ome cases (like with rots and potatoes) we would get awully sick if we didn't cock them before.
    On the other hand we can eat raw animal food.
    Our teeth and jaws don't look like that of a bird or a pig, nor does it look like a cow or a horse, or a cat or a dog. in fact it barely looks like that of a shimpanse.

    The human developed the ability to cook her food way before we developed agricultur. Therefore we are able to eat a huge variety of foodstuffs, from herbs and rots to animal products of different kind.

    We are supposed to eat nutrient and calorie dense food. Not half our weiht in greens each day. Or maybe you have the trunk size of a monkey? Or four stomaches like a cow? Or the need to throw it up and chew your food again?

  14. shaun
    Humans from evolution were designed to adapt for our diets depending where on earth we are living,as a specie we were not giving a specific diet to eat,our species learned from experience wot we could and could not eat,our jaw structure is different from any other specie as we are unique to evolution,since the first man there is proof we cooked foods and had the ability to digest both meat and plant etc,name me an animal wot can digest the same as a human,mankind is constantly evolving in many ways depending on where we live,we adapt to altitude, pressure ,temperature,oxygen levels,we were given an advanced brain to survive which we used,
    for example the first man would have been very active walking long distances,foresting hunting capturing food and basic surviving would have needed nutrients from both animals and plants berrys nuts etc.back to design of our teeth we have molars for chewing and canines for biting tearing of flesh ?,wot part of eating fruit and veg would we need canines for?
  15. Luke
    So low-fat beat low-carb in every respect? No interpretation required. Eat carbs, not fat.
    Reply: #116
  16. Zepp
    Nooee.. low calorie beats every other regime,, as long as you can stick to it.. but thats not long!
  17. Sandy
    I don't care for the fact that "sugar" and "carbs" are used interchangeably in this. For all processed sugars are carbs, not all carbs are processed sugars. The title should really be - "carbs vs. Fat". This does nothing to isolate processes sugar as an identifier to obesity and weight loss difficulty. The body NEEDS carbohydrates to function properly - it's all about which carbs you're ingesting.
  18. Mike
    Wile this is all true that humans are designed to eat fruit & veggie, our jaws/teeth are not designed for rough meat & our digestive system is not strong enough to eat raw meat chicken/beef/pork without geting sick, but.. Our system is stable enough to eat raw fish & sea food. So to add to the theory of human diets design I agree. We where not born/created with the theory of a stove or fire to cook our foods. Also as much as I love milk, I do agree it is liquid food for infants that can not chew or digest substance yet due to a weak digestive system. Grown adults should not drink milk in theory. No adult animals in the world drink milk after they pass the infant stage.
    Also our teeth are not made for tough meat, not many can say they have but have you ever tried to eat raw chicken ham or beef? I have not but I can imagine how impossible it would be with our "crunching teeth" not made for cutting or shredding. Reason we only prefer to eat "tender" meat like filet steak etc. Humans should eat fruit veggie & sea food. These foods have natural sugar, low fat & high protein. Unlike red meat wich is full of fat. Or chicken full of disease us humans can not eat without cooking.
  19. Galina L.
    Humans have not only teeth, but brains and hands. Pounding and cutting in pieces can make meat easy to eat even without cooking. There are dishes made with raw meat in almost every culture.
  20. shuaib
    This is very interested
  21. shuaibu muhammad Dan-kano
    I really enjoyed the show.....
  22. fats/weight solution
    I need someone who will educated me more on fats/weight reduction because am a little bit fat than last two months +2348180255262 and my E-mail shuaibmuhammad100@yahoo.com thanks and
    Reply: #123
  23. Zepp
    Try this.. its not perfect.. but a good try to explain what its all about!

    http://www.fitintegrity.com/uploads/9/5/1/6/9516119/no_sugar_no_starc...

  24. Roger the eater of Gods gifts
    Eat Drink and be Merry, in Moderation.

    Good Luck ! and Enjoy!

    Don't Worry be Happy!

  25. teak
    to the user to mention the Paleo diet, if you look up the actual Paleo diet and the original one you will see it includes numerous amounts of bugs! Is that what you eat? If not it is not even the real Paleo diet. I find it strange also how so many people still do not realize that vegetables them self contain more than enough protein without absolutely any cholesterol....man-made chemicals carcinogens and a slew of other crap.There is not one single benefit from eating meat or any animal products whatsoever. Not one. People often ask or say ...oh my god you don't eat meat how do you get protein? And I tell them the same way our strongest mammals on the planet do! With a plant based diet. I said based....which does not mean I do not enjoy the occasional treats of sweets or anything else.. ....in my opinion all of this is simple common sense. One ingredient Whole Foods. Lose the dead animal flesh and the other dairy crap that was meant to make a baby cow into a 2500 pound heifer!
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