Review finds that ‘filling up on fruit and veg’ to promote weight loss does not work

At the tail end of 2012, I wrote a blog post about the impact of emphasising fruit and vegetables in the diet. ‘Filling up of fruit and veg’ is often recommended as a weight loss tactic. But, as I explained in the blog post, I’m not sure this is good advice at all. I argued that the fundamental problem is that, for the most part, people tend not to find fruit and veg particularly filling and/or sustaining. Because of this, adding more fruit and vegetables into the diet does not necessarily translate into a reduction in the overall amount people eat.

In fact, in the blog post I report on a study in which both lean and overweight individuals were asked to emphasise fruit and vegetables in their diet, to see its effect on satiety and latency (the amount of time it takes before someone want to eat again) and overall food intake [1]. In short, what the study showed is that eating more fruit and veg did not lead to people eating less (in caloric terms) overall. Actually, the overall effect was for them to eat more and gain weight.

I was interested to read a related review published this week in the American Journal of Clinical Nutrition [2]. In it, US researchers collated evidence from a range of studies in which the emphasising of fruit and vegetables had been recommended to individuals with the goal of weight loss. A total of 7 studies were included as part of the review. The conclusion was that the studies simply do not support the proposition that adding more fruit and vegetables to the diet aids weight loss.

Why does fruit and veg fail to sustain? Well, while these foods can offer useful nutritional offerings (e.g. vitamins and other nutrients), they tend not to be rich in certain other elements that are essential to health including ‘essential amino acids’ (from protein) and ‘essential fats’. In essence, maybe the body knows that fruit and vegetables are lacking in dietary elements that are critical to our survival.

There is also some evidence that protein is the most sating and sustaining element of the diet (compared to carbohydrate and fat), and I certainly see evidence of this in the real world. This is one of the reasons why when talking to non-vegetarians, I recommend meaty soups over vegetables ones, and that if someone is going to eat a salad “it helps if there some animal in it.” Leaving aside the nutritional attributes of protein and fats in animal foods, the end result of eating these sorts of meals (as opposed to their ‘lighter’ versions) is usually that people feel more satisfied after eating (so perhaps less tendency to eat something else like cake, chocolate or crisps/chips straight after), as well as a feeling that they can go for longer without hunger biting again.

Fat, for some people, does seem to have some important sating properties. I’ve come across many individuals who will, for instance, not feel as sustained after eating a chicken breast as after eating a single chicken leg. The sating effects of protein and fat have been seen in a study which found that lower–carb diets lead to a significant spontaneous reduction in calorie intake, and that the more fat is eaten, generally the less is eaten quite naturally [3].

While this may not apply to all, I generally find that if people want to eat less without hunger, then some emphasis generally needs to be placed on foods rich in protein and fat. To be honest, for most people, fruit and veg just does not cut it.

References:

1.    Houchins JA, et al. Effects of fruit and vegetable, consumed in solid vs beverage forms, on acute and chronic appetitive responses in lean and obese adults. Int J Obes advance online publication 2013;37(8):1109-15

2.    Kaiser KA, et al. Increased fruit and vegetable intake has no discernible effect on weight loss: a systematic review and meta-analysis Am J Clin Nutr 2014 First published online 25 June 2014

3.    Johnstone AM, et al. Effects of a high-protein ketogenic diet on hunger, appetite, and weight loss in obese men feeding ad libitum. AJCN 2008;87:44-55

22 Responses to Review finds that ‘filling up on fruit and veg’ to promote weight loss does not work

  1. Vanessa 27 June 2014 at 6:55 pm #

    When I have salads for lunch at work, I always include a home-made oil/vinegar dressing and some meat/fish and cheese cubes – keeps me satisfied until tea time. Also when having cooked veg, melted butter does the trick (no potatoes or other carbs, just meat, fish or eggs) – and adding cream to vegetable soup is also helpful.

  2. ValerieH 27 June 2014 at 7:03 pm #

    I wonder if the study people ate more fruits than vegetables? Maybe that increased their desire to eat. I have found success in losing weight more often when I eat vegetables while cutting carbs. I add a lot of fat to them :)

  3. Paul 27 June 2014 at 8:16 pm #

    If one wanders around a supermarket these days, looking for a pre-prepared ‘salad’ to eat for lunch, the salad is usually comprised 70% pasta, and 30% vegetable matter.

    I don’t know of any salad recipe (in a recipe book) that is based on 70% processed carbohydrates, but the supermarkets know that carbs are cheap and have a long shelf-life, AND can be sold as ‘low fat’.

    I fear that only people who can prepare their own food stand any chance of maintaining weight and health, and those who are restricted to buying pre-prepared food from food stores are sold ‘junk’, masquerading as ‘healthy’.

    • Lori Miller 28 June 2014 at 1:00 am #

      Great post! I see people commenting all the time that they’re eating “tons of veggies” and wondering why their LC diet isn’t working for them. Non-starchy vegetables may be low carb, but they’re not NO-carb. Cups and cups of vegetables add up to scores of carbs. The blog post I wrote just yesterday addresses this topic among other pitfalls people encounter on LC diets:

      http://relievemypain.blogspot.com/2014/06/what-is-atkins-anyway-definition-and.html

  4. Nigel Kinbrum 27 June 2014 at 8:56 pm #

    Hi,

    Without knowing exactly what veggies & fruits were eaten, you shouldn’t claim that all veggies & fruits are worthless for weight loss. A sweet potato microwaved in its jacket is very filling (if you eat the jacket!).

    Cheers, Nige

    • Dr John Briffa 29 June 2014 at 3:38 pm #

      Hi Nigel

      “you shouldn’t claim that all veggies & fruits are worthless for weight loss.”

      I didn’t claim anything of the sort, and it’s disappointing for you to start your comment with a straw man.

      Thanks for the anecdote about sweet potatoes, though.

      Here’s another one: some people find that eating sweet potatoes (even with their jackets on) are quite destabilising for their blood sugar levels and can lead them hypoglyaemic and hungry again 1-3 hours after eating them.

      • Stephen Rhodes 29 June 2014 at 6:47 pm #

        Would you know is any attempt has been made to find out whether those who suffer destabilising of their blood sugar levels are the cohort with few copies of the AMY1 gene coding for Amylase in the saliva? The corollary being “is there a cohort that has many copies of the AMY1 gene that does not suffer erratic blood sugar levels after eating Sweet Potato?”

        There does appear to be some potential in the determining the number of copies of AMY1 an individual has, in order to give dietary advice that actually helps!

  5. Norah Ethel Coleman 27 June 2014 at 9:30 pm #

    My husband and I are both diabetics and although our Endocrinologist insists we should eat 50 grams of some carb at every meal, personally I tend to skip this unnecessary filler. I do very well on meat and salads or cooked vegetables such as spinach, kale, zuchinni, aubergines and soups with lots of grated vegetables (not the starchy ones, of course). And in summer, meat and salad. Not necesarily beef. We eat pork, veal, fish, lamb, and always prepared either grilled or roast – no fried stuff to stink the house out, thanks. And this year we entered into the habit of eating cantaloupe melon for dinner – half a melon each. It has really made a difference and we have noticed some weight loss. Perhaps it is due to the fact that in Uruguay, people eat dinner rather late, so about an hour or so later, we go to bed and that doesn’t let us nibble on things we shouldn’t eat after dinner.
    But I do agree that some kind of protein – an egg, a piece of cheese or some ham are necessary at the other meals.

  6. Yossi 28 June 2014 at 8:26 am #

    I remember that you praised Jonathan Bailor’s book “The Calorie Myth” earlier this year. Jonathan’s advice to readers is to eat at least 8 portions of veggies per day and further recommends making smoothies to get as many veggies inside you as possible. I wonder whether you might want to revise your recommendation of his book?

    • Dr John Briffa 29 June 2014 at 3:33 pm #

      Yossi – I don’t recall Jonathan Bailor arguing for the inclusion of plenty of vegetables in the diet on account of their appetite-sating effects, though.

  7. kathy 28 June 2014 at 1:36 pm #

    A friend of mine has just been diagnosed ith type 2 diabetes. She’s a substantial lady, and the main reason for developing diabetes, she has been told, is that she eats too much fruit – which bears out the ‘cutting back on fructose ‘ message,

  8. William L. Wilson, M.D. 28 June 2014 at 3:25 pm #

    I agree that trying to fill up on fruits and vegetables is a lost cause. On the other hand, when people do try to follow a low carb or ketogenic diet, it’s important to shift the carbs you do eat to fruits and vegetables rather than grains or other high glycemic carbohydrates.

    Another trick is to fry your vegetables in coconut oil. That way you get the benefits of the vegetables along with the filling effect of the fat.

  9. Pamela 28 June 2014 at 8:37 pm #

    Absolutely right! When I began my weight loss endeavor, I started pure vegetarian. I lost weight dramatically, but I had to eat all day to suppress the hunger. As long as I ate only fruits and veggies it did the trick for me, regardless of the quantities I ate. Later I added some lean meat, fish, chicken and olive oil. That went even better. I kept weight without feeling hunger. Just avoid the concentrated carbs.

  10. Lynn van Dyke 29 June 2014 at 9:14 am #

    I’d just like to say that I am 66, I was a vegetarian for 35 years for ethical reasons initially. I was healthy enough but had high cholesterol. I was on statins. I had pains and felt the statins were to blame. Coincidentally I had decided to be vegan at this time as I am against factory farming. When I had my cholesterol tested after changing to a vegan diet it had lowered to normal. I am as fit as a fiddle and am told I look 50. I make sure I get my omegas from ground flax (my body obviously has adapted) and get enough B12 and although my meat eating relatives have diabetes, osteoarthritis, arteriosclerosis and cancer, I am without any of these aging complaints. Animal products may satiate but so do plant proteins. Beans, legumes, soya, tofu and other substitutes do the trick and you won’t end up with those diseases!

    • Lori Miller 29 June 2014 at 9:04 pm #

      Respectfully, vegans and vegetarians are generally very health conscious. Meat eaters, who make up over 90% of the population, are all over the board. When you try to compare vegetarians to meat eaters, there are confounding variables left, right and center.

  11. NM 29 June 2014 at 3:47 pm #

    “Fruit and vegetables” have a halo that extends well beyond any strong evidence of their healthful efficacy. Furthermore, logic dictates that, as a species funnelled through a long and strenuous ice-age, we simply must not have to rely on them sine-qua-non in the way that banal opinion suggests.

    Certainly, fruit and vegetables DO appear to offer a number of benefits with regard to phytonutrients and so forth; but something beyond science must explain the hysterical adulation that surrounds them. This is particularly true when one considers that non-epidemiological, properly controlled trials rarely show any particularly exciting health benefits for fruit and vegetables. Even typing that sentence – which is accurate and true – feels subversive, almost blasphemous.

    This vegetative adulation existed long before any evidence-base – however spurious and confounded – existed. In fact, the evidence-base seems to derive from the needs of the meme rather than vice-versa! This indicates that the disproportionate worship of fruits and vegetables is more cultural than scientific. And, indeed, they have long been a symbol of pre-lapsarian innocence. In Judeochristian mythos, the Garden of Eden was a vegetarian paradise; the notion of our becoming “sinful meat-eaters” after our Fall therefrom has a long and powerful presence in our culture. The very word “carnal” derives from the same root as carnival, meaning “flesh”. Whether the flesh of an animal, or of another human, much Christian theology was profoundly influenced by Gnostic abhorrence – an abhorrence which did not extend to fruits and vegetables except, of course, at the very moment of the Fall, when Eve offered to Adam the one fruit forbidden to humanity.

    Of course, this religious mythology is nonsense; but it is a powerfully influential memetic toolkit which nutrition scientists subconsciously channel daily. Thus, it’s profoundly easy for a researcher to slot a “Red Meat Will Kill You [and damn your mortal soul]” into the cultural narrative. It’s simple for a journal to publish a “Fruit and Vegetables Could be Your Health [and eternal] Salvation”. That this all seems to slide into conventional wisdom so easily makes use of a lubricant much older and more effective than the Seven Countries Study!

    Lust, Original Sin and bodily pleasure have long been associated with meat-eating and related “sumptuary excess” in Western tradition, with fruit and vegetables a counterbalancing yearnful hope for a return to Edenic innocence.

    So whether we’re discussing the cynical “Five a Day” scheme, or the even more cynical attempt to pretend that a “Mediterranean Diet” is primarily vegetables and “wholegrains”, it behoves one to remember that we’re dealing with symbolism that pre-dates even Ancel Keys by several millennia, and that to question its validity is thus just as subversive as it feels.

    • snowmoonelk 30 June 2014 at 1:41 am #

      Blimey!

  12. NM 29 June 2014 at 4:47 pm #

    Lynn van Dyke: your health at the moment is not related to your rejection of meat; nor is the lack of health in your relatives related to their consumption of meat.

    Rather, you are enjoying the healthy actor effect. Let me try a bit of Mystic Fortune Telling:
    You don’t smoke.
    You exercise sensibly.
    You look after yourself.
    You don’t eat lots of junk-food.
    You limit the amount of added-sugar you consume.
    You are careful to sleep well.

    I bet I got a lot of those right. Just call me psychic!

  13. Mark John 29 June 2014 at 10:08 pm #

    I’m not entirely convinced by much of your analysis NM.

    A few decades ago everyone knew that butter, eggs, meat etc were healthy. In fact when people were ill with consumption (TB) the “cure” was a rich diet. Everyone also knew that root vegetables were fattening and other vegetables were secondary to a rich diet. Fruit was eaten when in season and available.

    It’s the heavy marketing behind the 5 a day message sponsored by vested interests which has cemented that fruit and vegetables are “supremely healthy” in the modern mind. Turn the clock back any number of centuries and vegetables weren’t really eaten in preference to a “rich diet” when such a rich diet was available.

  14. NM 30 June 2014 at 10:36 am #

    Mark: my analysis isn’t actually controversial. I do agree, though, that a number of paradoxes abide. You see, the very fact that butter, eggs, meat and so forth made one feel vibrant and – dare one say it – even frisky – was a strike against them in the more ascetic sectors of religion. Yes, fruit and vegetables “cool the blood” so to speak, and enervate one entirely without the concomitant fat and protein! This dulling effect would have been considered a net *benefit* to your average Puritan. That Lent eschews meat, as do some Churches every Friday, indicates the relationship with this suspiciously opulent, fleshly delight. Carnality, carnivorism, meat as red as the devil.

    Now, why such a mythos should emerge is more complicated, and beyond the realm of a blog comment. There were a number of political factors, as ever. Cynically, it was useful to convince the poor that the meagre veg and gruel that was their lot was actually spiritually *good* for them. “Those mutton joints that the Lord and Lady are enjoying might SEEM tempting, but as with all such temptations, they lead to Hell. So enjoy the spiritual purity in what little you have!” The church has often, through its more shameful history, tried to make the poor believe that they should not only accept their lot, but revel in those very discomforts and frugality as a down-payment for the Eternal reward! 19th Century vegetarianism plugged straight into this. It still does today, albeit unwittingly.

  15. Cindy 30 June 2014 at 1:48 pm #

    Thanks for including the comment about some people needing fat to feel full. I’m one of those people and it always surprises me that I can eat a piece of steak in a restaurant and still be hungry, but a small piece of cheese is all that I need to feel full. I don’t like to eat the fat on steak-makes me gag-and I always add butter, olive oil, or coconut oil when I cook steak at home. I think I’ll start asking for a side of butter with my steak when I go out. I stay away from fruit and veggies when I’m hungry. Eating those-especially lettuce-just makes me hungrier and cranky. I also have a hard time digesting anything when I load up on fruits and veggies and usually end up nauseated.

    Posts like these make it easier to follow what my body is trying to tell me instead of listening to all the talking heads around me. Thanks!

  16. @lowcarb_zealot 14 July 2014 at 12:36 pm #

    “Five a Day” is fine, as long as the five are avocados, coconuts, olives…..

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