The food we eat can perform a range of functions including an ability to nourish us and bring us pleasure. However, I reckon a sometimes forgotten quality of food is to sustain us. I’m not sure what the precise definition of sustain is, but if I were to have a stab at it I’d say something like “the ability of food to satisfy us, energise us, and stop us needing or thinking about food for an extended period of time.”
So, generally speaking, I advise people to opt for meals and snacks that are both nourishing and sustaining. The sustaining effect of food is sometimes forgotten, and this can lead people to eat foods they perceive to be healthy and nourishing, that unfortunately don’t get them very far in terms of sustenance.
As an example, imagine a big pile of spinach. Eat just this, and there’s a real risk that more food is going to be required in short order. Some people could, I think, eat a roomful of spinach and, however full their stomach, still feel hungry. And even if it did put a dent in someone’s appetite, the effect will generally be short-lived.
OK, that’s an extreme example, but some of us will attempt to subsist on meals that are not too far off this. How about carrot and coriander soup? Imagine if I offered you lunch in the form of a couple of carrots, half an onion and some water (because that’s essentially what a bowl of carrot and coriander soup is). How far is that going to get you? When I ask this question to people in the real world the vast majority smile and say “not very far”. Intuitively, they know that some veggie soup is unlikely to really hit the spot.
It is this phenomenon that causes me to not be too enthusiastic about using fruit as a snack. The fact is, fruit does not do a generally very good job of sating and sustaining people. And I’d say that’s a problem seeing as a major reason for having the snack should be to sate the appetite properly and tide one over nicely to the next meal.
The failure of fruit and veg to sustain is also why my eyes roll upwards when I hear weight loss experts or health professionals recommend that people eat plenty of vegetables and fruit because “the fibre helps fill you up and keep you full for longer.” My experience, as I’ve said, is that this is largely bullshit.
And so I was interested to read about a recently published 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.
Part of the experiment involved getting people to consume fruit before a meal, either as solid fruit (fresh and dried fruit) or fruit juice. Neither approach seemed to lead to less food being consumed, and the effect of the fruit juice was worse than that of the solid fruit.
Let me be clear and state that I don’t think vegetables are unhealthy overall. I do think they’re relatively nutritious foods but the fact is they don’t do much to sustain on their own. Some solid fruit may be OK too, though its sugary nature means I don’t recommend it is particularly emphasised in the diet, particularly in individuals who may have sugar-related issues such as obesity or diabetes.
There is some science which points to protein as being the most sating and sustaining element of the diet (compared to carbohydrate and fat). 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.
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, November 20, 2012
