A Snacking Craze

This particular post is the result of a challenge issued by ex-lab buddy @foetalgod. He has pretty good credentials in this field as, when we were lab mates, he was focussing on insulin, metabolism and blood glucose. I was his insulin-making bitch-monkey. He’s also a successful dieter.

The challenge was to look into the scientific claims made by the snack delivery company Graze. The company sends out reasonably priced snack boxes (free postage), largely containing healthy snacks – dried fruit, seeds and nuts. They also do really nice flapjacks (anyone who has ever made flapjacks will know how much sugar, syrup and butter goes in). Apparently. These are noble aims indeed. As a nation, the British are getting fatter. According to an NHS report published last year, in 2008 almost one quarter of the English adult population were obese and over half the adult population was overweight. This is primarily due to physical inactivity and an unhealthy diet; for example only 25 % of men and 29 % of women were eating 5 or more portions of fruit or veg every day. The official advice is to reduce consumption of sugar, saturated fat and salt and to increase intake of whole-grain foods, fruits and vegetables. As well as exercise more. Right.

A first glance at the Graze website and it’s all very friendly – it’s a nice site, the postage is free. And, according to the site, the consumption of their snack foods throughout the day provide the following benefits:

graze for good energy > Grazing is a great way to ensure you have good energy all day long

help you lose weight > Grazing can be a great way to help you lose weight by stabilising blood sugar and making you more efficient at burning fat

boost immunity > Grazing on our natural foods is an excellent way of boosting your immunity by filling in vital nutrients that may be missed due to skipped meals and long busy days at work

varied & balanced diet > Grazing on a wide variety of smaller portions of food will help give you more balance and variety for a healthier diet

80/20 rule > Nobody is perfect, and who would want to be?

The last three points I take no issue with. I can’t argue that the interesting and varied snacks that Graze provide will lead to a more varied diet. Yes, nutrients provided by the Graze snacks may help the immune system if you are deficient in them. And, yes, it’s fine to occasionally eat things that are bad for you as long as you eat well the rest of the time. It’s the rest of those points. They seem to be making claims, which, seeing as there are no references to any scientific research at all, for which they’ve provided no evidence. I thought I would investigate each claim using scientific evidence.

“Blood Sugar”

OK, good energy? Is that like the force? Jedi use the good energy and Sith use the bad energy? This is the first time that Graze invoke the magic words “blood sugar”. Most of their snacks “release energy slowly” – I presume they mean that the glucose contained in these foods is slowly absorbed by the gut. Then they wave these pretty graphs in front of us:

They look good – blood sugar levels are more stable if you “graze”. But hang on a minute; where did this data come from? What are these people eating? Where are the numbers? Like the rest of the Graze site, there are no references. I did some rummaging on the internet; even Wikipedia has a better graph than this. However, I found exactly what I was looking for in a couple of papers.

Mean plasma glucose for the group of nine volunteers (mean+SE) Arrows indicate timing of meal presentation, and bars represent the sleep period.

This figure was taken from Biston et al 1996. The researches took 9 young healthy volunteers, took blood samples every 20 mins to test their blood glucose levels. Over the 24 hours during which blood sugar was being monitored, the volunteers ate 3 identical carb rich meals (the paper described the precise composition of the meals). So yeah, as you can see, blood sugar increases after meals (meal times are indicated by the arrows). The blood glucose levels drop after meals because insulin is also released. Insulin causes glucose to be taken up by the liver and muscles so it can be stored until it’s needed later. You can seen that with the meals eaten here, it takes a while for the blood glucose levels to fall. There doesn’t seem to be a 3pm chocolate time. Also, as you can seen from the graph below, release of insulin mirrors blood glucose levels very closely.

High levels of glucose in the blood are dangerous: it can affect the concentration of substances important to biological processes required for life. If levels are too high for too long, over many years, high blood sugar can lead to organ damage – this is often seen in people with diabetes. Diabetes, blood sugar and insulin are inextricably linked; type 2 diabetes occurs as a result of loss of insulin sensitivity by the cells of the body, and fluctuating blood glucose levels are a causative factor. The body knows that the best thing to do with excess glucose is to store it. So insulin is released from the pancreas and it stimulates the uptake of glucose into the liver and muscles so that is can be stored for use later. The amounts of insulin released into the blood shows a similar pattern to levels of glucose in the blood, because it is important that the body tightly regulates glucose. Low blood glucose is extremely dangerous and can lead to coma and death as the brain must have glucose to function.

But not all diets are equal, and I guess that this is one of the thing Graze allude to in their foods that “release energy slowly”

Diurnal profile of blood glucose concentrations with the high-starch and high-sucrose diets. Mean ± SEM; n = 8

Daly et al 1998 looked at the effects of a high sucrose (sugar) diet versus a high starch diet on blood sugar levels and found that in those subjects on a high-sucrose diet, blood sugar fluctuated a lot more. In the meals eaten by the volunteers, there were no differences in fat or protein. This would be the “chocolate bar” effect. Eating high-starch, rather than high-sucrose meals kept blood glucose levels more stable, and blood sugar levels do not nose-dive to pre-food levels.

When foods are converted into glucose quickly, the body reacts by releasing loads of insulin. Insulin is the catalyst that converts sugar into fat and stops the body from burning it.

Well, they’re half right. But they are completely wrong about insulin. It is not a catalyst that converts sugar into fat. It is signalling molecule that tells the muscles and liver to take up sugar from the blood. The sugar is then converted to to glycogen so it can be stored, the “catalyst” or enzyme for this is glycogen synthase. When there is a lot of glucose, the glucose is converted to fat by a very complicated process shown in the diagram below (Help! I’m having biochemistry flashbacks! Make it stop! Make it stop!)

I propose, instead, that many eat between meals out of either boredom – you’re stuck in an office working, eating is something to do, unhealthy food is easily accessibly – or because many don’t eat properly at lunch (or skip lunch entirely) causing havoc with blood sugar levels. From experience, I know I eat what food is available. With the Graze snacks, most of them are healthy. But man cannot live on seeds alone, so eat a decent lunch.

Does “grazing” make you more efficient at burning fat? Well, despite this being the gospel pushed by flakey diet books, I am struggling to find scientific evidence that a low glycaemic diet and/or frequent meals (which causes fewer fluctuations in blood glucose levels), actually make fat burning more efficient. The statement is ambiguous and essentially meaningless. However, there’s evidence that implies that break down of fat is reduced when insulin levels are high. So, in a manner of speaking this is true. Maybe.

Miscellaneous cackwaffle

There are other points along the site that SCREAM bullcrap. Yes, I’m nit-picking, but if they did their research (or at least cited their information sources) they’d have some defence. Firstly, there’s the 4 Box Detox – this is hidden away somewhere on the site so I can’t properly whine about it, but you can read here for my take on detox. And it’s something that has been covered in depth elsewhere.

They have a list:

Here are our top tips to help keep blood sugar within the green zone:

  • never skip breakfast — it really is the most important meal of the day
  • eat natural (unrefined) foods
  • drink less tea and coffee (they are stimulants that mess with your blood sugar)
  • drink more water
  • eat whole fruits rather than juices
  • remember fibre is your friend!
  • try to cut down smoking
  • eat slowly — chew your food to release all that energy
  • don’t skip meals

I have a minor issue with the drink more water point, merely because it harks back to the “drink 8 glasses of water a day” myth.

But “drink less tea and coffee” HOW VERY DARE THEY! Yes, both contain caffeine, this is true. It has been proved repeatedly that coffee increases both insulin and glucose levels after eating. Curiously, there is an increasing amount of evidence that coffee may have beneficial effects in patients with type 2 diabetes (and this).

Black tea contains phenol compounds that inhibit alpha-glucosidase, an enzyme the breaks down sucrose to glucose in the small intestine, these phenol compounds in the tea slow the conversion to glucose (the form of sugar your body uses), which would slow down the rise in blood glucose levels after a meal. When you try this in humans, tea lowers the spike in blood glucose after a meal. So there. Check your facts Graze.

I would, however, kill for one of their honeycomb flapjacks right about now…

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