Diets: Sorting fact from fiction

With so much dietary information out there, how do we know what's food fact and what's fiction?...
22 August 2017

Interview with 

Rebecca McManamon




When it comes to food it’s difficult not to be overwhelmed by the sheer volume of dietary information out there. To separate food fact from fiction, and to find out what really does constitute a healthy diet, Chris Smith spoke with dietician Rebecca McManamon.

Rebecca -  People think that diet means some kind of a restrictive diet which, in some senses, it might be, but really diet is describing our eating pattern overall - what we need to nourish our body. We need to have a real balance of things.

Chris - When you say “balance,” what do you actually mean by balance? What constitutes what a doctor would regard as eating a healthy diet?

Rebecca - Certainly lots of fruits and vegetables. We know in this country children and adults don’t eat enough fruit and vegetables and that increases our risk of chronic diseases. But also it’s about a mix of other foods, so thinking about our proteins. Things like oily fish are beneficial, whitefish, all sorts of meats, but also our plant based proteins, nuts and seeds, soya for example - all those other kinds of proteins.

There are other components to our diets, so thinking about our carbohydrates which have certainly had a lot of bad press in recent years. But, let’s not forget that carbohydrates we need for energy and also they’re a source of fibre. Something, again, we don’t really get enough of and which is beneficial to us. So we do need some carbohydrate in our diet but perhaps in recent years we’ve been eating more than we need and there’s a lot of processed carbohydrates out there.

Chris - When I went to medical school they put up a graph and it said this is the number of calories you need in a day. If you’re a man it’s 2,000/2,500 and you should get about half of that from carbohydrates. You should get about a fifth of that pie (20%) from proteins, and the third left should be, give or take, the fats. Does that still hold?

Rebecca - We probably don’t need as much carbohydrate as 50% of our diet and fat, again, is another really interesting area. For example, the low fat diet has previously in the 80s and 90s thought to be the way that we should deal with chronic diseases but, perhaps, fat can be beneficial. But, like any food, if we’ve got too much of it we do need to be cautious.

Chris - A little bit confusing, isn’t it, because carbohydrate does include highly refined, processed sugar but it’s also starches and complex sugary based things which are harder to break down and, therefore, they’re called carbohydrates, but they’re not as energy dense or they don’t release as many calories all at once? You mentioned fruit earlier and vegetables as well. A lot of people say well, I’ll substitute a smoothie. I’ll eat smoothies and things, that’s full of fruit and vegetables. But I’ve just got one we got from the shop around the corner. The amount of energy in this is huge.

Rebecca - Definitely. It might even be similar to some popular fizzy drinks in those calories and the amount of carbohydrate that’s there which can go into your bloodstream quite quickly. You’re missing out potentially the fibre when you’re having smoothies and that time that we take to enjoy our food. That’s something that we forget about diets is that food is to be enjoyed, it’s pleasurable, and it’s very sociable.

They do still have a place if somebody really can’t eat fruits and vegetable, and even for some of my clients that need to gain weight. We also forget that malnutrition is still a problem in the UK.

Chris - Now flipping it round to the other side of the equation - people who may wish to shed a bit of weight. I’ve got sitting on the table with me some examples of a few diets. Let’s talk about the paleo diet first of all. What’s that just briefly?

Rebecca - The paleo diet, or the caveman diet, is thought to be all about going back to the times when we did live in caves and our diets were very basic. Maybe we didn’t have grains in our diet and it’s this belief that this is going to be a more beneficial thing.

Chris - I’ve got some pumpkin seeds here, and some chicken chunks, and few bits of nice crunchy carrot. This is, ostensively, part of the paleo diet - is that any good?

Rebecca - Certainly those are good aspects, and certainly thinking that the paleo diet believes that you shouldn’t have much salt or processed foods, certainly those are good things. But foods that contain grains, they also have fibre. We also know that some benefits like, for example, oats, there’s a lot of research that that can help lower our cholesterol if we eat oats on a regular basis.

To restrict a food group is worrying because then what are we missing out on? There’s very little data to show that this paleolithic diet is actually going to be of benefit for our health.

Chris - What about the 5:2 diet? Because this has got a lot of advocates; people who eat for five days normally, as they dub it, and then have two days of very profound calorie restriction. Is there merit in that?

Rebecca - Certainly there’s been research at the University of Manchester into this with breast cancer that it may help in the prevention of recurrence of breast cancer because that’s related to obesity and, also, insulin levels in the 5:2 diet can reduce insulin levels. For the general population, we’re not so sure if it’s the best for everyone.

Chris - We’ve considered so far the paleo diet, we’ve looked at this 5:2 diet and whether or not that might work but there is one other diet. I have to admit I’d never heard of this but then I’m not dieting. That’s this alkaline diet - now what’s that?

Rebecca - The professed way that the alkaline diet may help you is that it would alter your Ph, and this worry that if we have acidic foods that this is going to be negative to our body but, actually, there’s really no scientific grounding in this. We all know about homeostasis and, ultimately, that’s what our kidneys and the rest of our organs are going to be working in combination to do, is keep the Ph of our blood very stable, otherwise we’d become pretty ill.

Chris - Yes. One of the items - I’ve got here some kale, I’ve got some walnuts. Those are apparently part of the alkaline diet, and an orange. I was quite surprised that an orange, which is obviously quite low Ph, isn’t it, it’s full of acid, that would be on the alkaline diet? Is this an example of charletons just flogging us an idea - it’s not really underpinned by decent science?

Rebecca - No, it’s not underpinned by science. In the 70s, 80s there was some view that this was actually called the acid hash hypothesis, that acidic foods perhaps would be bad for our bone bone density. But that’s been very much disproven now. One of the things that alkaline diet advises you not to eat is dairy foods which, of course, if we know of someone who was going to restrict dairy, and also some protein is advised to be restricted in this diet, then that would certainly not be good news for our bones.


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