The Truth About Food

By Jim F


The BBC have made every episode of TV series “The Truth About Food” available on-line. The series explores the various myths and ideas about food and diet.

As part of the series the producers performed various experiments on different people to determine what actually happened.

Here are a few interesting “discoveries”.Does Increased Fiber Do Anything?
Increasing the fiber intake of two subjects (up to 50 grams a day) dramatically decreased the time it took to digest food (from ~40 hours to ~20 hours).

Water Consumption
They took someone who drank 2 liters of bottled water a day, and stopped them from drinking the extra water. The result? Nothing. No change in skin tone. The producers felt that the water we receive from food, and other beverages was completely adequate for the average (inactive) person.

Fart Power
The average person expels 1/2 liter to 3 liters of gas a day (I’m sure you’ve been burning to know this – but were too afraid to ask). I just hope you don’t share an office cubicle with the person who has a 3 liter-a-day habit.

Does Increased Protein Help?
Producers fed volunteers either a high-carb or higher protein meal for breakfast. The one who had the higher protein subsequently ate less at lunchtime.

Heavier Weight Due to Lowered Metabolism?
The food intake of two women were monitored. The thinner woman ate 50% less than her heavier counterpart. The producers felt that they could debunk “lowered metabolism” as a cause of weight gain:

the larger you are the higher your metabolic rate, the amount of energy your body uses at complete rest, will be. This is because when your body is at complete rest larger people need more energy to pump the blood around the body and to keep moving.

See more about the show or see the episodes.


  1. Dean

    I just finished watching an episode of this series where several people, all having cholesterol problems, underwent the “Ape” diet. Incredibly the cholesterol was reduced, in one case by an amazing 22%. Though the dietician in charge took credit for the reduction I can’t believe how naive the programmers were in not pointing out the totally different lifestyle of the participants. How can you have an objective test of diet when you have removed the subjects from the day-to-day stresses of their lives? This was, more than anything, a holiday in very pleasant surroundings which was of potentially more benefit than the diet itself. Absolute rubbish!

  2. rhoda

    If a thin woman eats half as much as a fat woman, how much of the weight difference is a caloric difference depends upon whether the difference in their weights is a factor of more or less than two. If a woman who weighs 105 pounds eats half as much as one who weighs 325, then there is much more to the weight gap than calories. But if the thin one weighs 129 and the heavy one weighs 190 or so, then some other factor is actually compensating partially.

  3. Vic

    I always make sure that drink at least 8 glasses of water a day. At first, I doubt that drinking too much water will cause something. But now that it has been proven, there’s nothing to worry about.

  4. virg

    50 g fiber/day won’t kill you, but there may be a problem with absorbing nutrients from dietary supplements since the fiber tends to bind with things and the food does rocket through your system much more rapidly. I eat anywhere from 40-50g fiber daily and the best part is that everything goes through much more smoothly, and my tummy stays flatter. There’s probably a point of diminishing returns (LOL) at higher levels because of the malabsorbtion of vitamins and minerals (or even medications taken with meals). However, our digestive systems evolved to eat lots of fresh (and fiberful) fruits and veggies, so 50g/day would not be outrageous. If you’re having problems with high fiber intake, it’s probably a matter of a rapid change in diet if your body had been used to much lower levels. Slow conditioning is crucial.

  5. Alex

    Interesting facts. I guess there’s no reason for to minimize drinking water. The only problem with drinking too much water is too many visits to the bathroom.

  6. Diet Plans

    I am wondering more about this fiber intake. Can’t taking over 50g of fiber actually harm you? Very interesting nonetheless.

  7. mia

    jp said:
    Let me rephrase to say…I would hate to see a lot of people start to preach that drinking excess water was not necessary because of a one person experiment that the BBC conducted. You can hardly call that a “myth debunked”!

    It really irritates me when one study, or article comes out about something, then all of a sudden everyone is on that bandwagon. […]

    the tv show didn’t even have enough of a following to get the idea of not having to consume much water any attention at all. bear in mind these shows aired a while ago and they didn’t stir a reaction in the public over here whatsoever. if anybody was influenced by the show, it was most likely a slim few out of the already small audience it had.

  8. Deb

    I think the 50g or so of fiber that they fed their subjects is the reason for the decrease in digestion time – I kinda live by “too much of a good thing is probably not such a good thing”. Fiber is my friend 🙂

  9. jp

    They only thing the article mentioned they observed with the difference in water intake was change in skin tone. There has to be other benefits to drinking water than that. I would hate to see exuse to not drink water.

    Truthfully, I don’t really care what other people do. Let me rephrase to say…I would hate to see a lot of people start to preach that drinking excess water was not necessary because of a one person experiment that the BBC conducted. You can hardly call that a “myth debunked”!

    It really irritates me when one study, or article comes out about something, then all of a sudden everyone is on that bandwagon.

  10. mia

    i love this show. i used to watch it when ever it came on. i think it’s a very interesting show. i actually wathched the one where they took the larger friend and the skinnier one. even though it seemed like the thin woman was always eating, when monitored it turned out she was actually consuming 50% less calories than her overweight friend. lol the larger friend was surprised. i always here overweight people say their skinny friends are constantly eating junk and they remain thin. but after watching the show i always have to wonder if the larger person is just underestimating how much they really eat or if their skinny friend is actually just a lot more active than they are. the “slow” metabolism excuse is one i would have used a while ago when in reality i was just extrememly lazy and blamed anything that was out of control on the size that i was. i don’t doubt some people are naturally thinner than others but i dont think anybody is naturally supposed to be very overweight (in the sense of having a high body fat %) or obese.

  11. Spectra

    I definitely know about the fiber one. It really speeds up your system. I eat a lot of fiber and I think food probably stays in my system for maybe 12 hours at the most. I go every day but my husband (who eats about 2 grams a day on a good day) goes like once a week.

    The metabolism thing is also very true. When I was bigger, I could totally eat more than I do now…my metabolism was probably higher because I had more mass to nourish.

  12. Talia Mana, Centre for Emotional Well-Being

    I love that show. I’ve watched every episode and enjoyed all their experiments. Great to see so many food myths debunked

  13. Jim

    Terry Wilson-Malam said:
    The only thing I don’t agree with is the water one[…]

    I’ve been working on a larger post about water intake coming up soon. It’s a very interesting subject indeed.

    Nate Cavanaugh said:
    And I too am curious about the digestion time listed.[…]

    My bad. Increasing fiber caused a dramatic DECREASE in digestion time.

  14. Nate Cavanaugh

    “The only thing I don’t agree with is the water one.”

    While there may be some unknown, or imperceivable benefits to your water drinking, a lot of the perception is probably a placebo effect (well, except the hunger. I notice when I have a stomach full of liquid, food doesn’t seem as appealing).

    I only say this so that you can enjoy your placebo effect without becoming a water nazi, and telling everyone that they don’t get enough water.

    People seem to sometimes confuse what they enjoy with what everyone else should enjoy.

    Just a thought 🙂

    And I too am curious about the digestion time listed.

    I guess the bottom line, since the numbers and semantics aren’t clear, did fiber help or hinder?

  15. James

    Very interesting about the water.

  16. Crabby McSlacker

    Thanks so much for telling us some of the highlights!

    I don’t know why, but I’d really rather read things than watch a video, especially on the web. So I miss out on newsy things that are buried inside programs.

    I’m surprised, though, on the metablolism thing, that they’d make such a huge generalization based on comparing just two women. Are they trying to say people really don’t have different metabolisms, that it’s all just calories in, calories out? Because I think a lot of people would disagree with that. Or did they have a bigger study to back it up? Seems perhaps a bit irresponsible.

  17. Terry Wilson-Malam

    Did you mean that it decreased digestion time from 40 to 20 hours or increased from 20 to 40? The only thing I don’t agree with is the water one. Although I feel I don’t drink enough water, when I do, I do feel better in so many ways (including skin tone) but most importantly, if I drink enough water, regularly, I’m not as phantomly hungry. It’s almost like magic.

  18. Never teh Bride

    Fiber has, er, another function of course. I try to get a lot of fiber through whole foods because bad things happen when I don’t. I won’t get into what those bad things are, of course, but I could have told them that increased fiber does do ‘something’ for those of us with, um, elimination issues.

  19. Neel

    Fun facts!Especially the 3 litre story…:)

  20. staci

    well, i feel better knowing that because i dont get exactly 8 glasses of water every day that its not a bad thing, but not good either. i also like that protein effects appetite. does it depend on what type of protein? i feel that beef products (more than 2 days a week) tend to make me feel very lazy- but when i eat poultry or more veggies in a week, i feel more energized, like i could still run a marathon at 11pm.

  21. Lose Weight With Me

    Interesting about the water! i don’t think I’d like to replicate that test, though. I can’t imagine NOT drinking a lot of water.


  22. Fitness Guy

    I reckon I put out a bit more gas than that!

    It is a good series though isn’t it.