This post is part of a short series about?the nutrition material I was required to learn?for my personal training qualification. ?In this post, I?m going to have a quick look at the course material that tried to teach us how to evaluate various diets from a health perspective.? The course notes look a number of diets, including:
- Atkins (and other low-carb diets)
- Zone
- Blood group
- Food combining
- Meal replacements and diet clubs (like Slim Fast etc.)
I detail below the key points in my course notes about the above issues and then comment on what I think are the interesting questions.
If you are curious, here?are the rest of my posts about my?personal training qualification.
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My course notes
My course notes cover a small number of popular diets and makes the following comments:
- Atkins: my course notes observe that:
- The diet allows unlimited amounts of protein and fat but no carbohydrates, as carbohydrates cause over-production of insulin, which leads to increased hunger, over-eating and weight gain
- Research suggests that low-carbohydrate diets could help certain individuals to maximise fat loss
- Low carbohydrate diets lead to glycogen loss, which leads to weight reductions
- Disadvantages may include:
- Problems for people with weak kidneys (high protein)
- American Heart Association does not endorse it (saturated fat content)
- Deficiency in certain vitamins and minerals
- Deficiency in fibre
- Deficiency in antioxidants and phytochemicals
- High in saturated fat (but research shows that this does not cause a rise in cholesterol)
- Difficult for vegetarians
- Reduces variety of foods that may be eaten
- Not sustainable
- Expensive
- Not suitable for the ?regular exerciser?
- Zone: my course notes observe that:
- The diet plan is based on a macronutrient profile of 40% carbohydrates, 30% protein and 30% fat, which is therefore described as a high-protein, low carbohydrate diet
- Disadvantages may include:
- Problems for people with weak kidneys (high protein)
- Expensive
- For an interesting defence of the Zone Diet, check out my top ten articles by Lon Kilgore and the article he wrote about physics, physiology and food
- Blood Group: my course notes observe that this diet plan assumes that our different blood groups evolved over time and reflect different phases in our evolutionary development, as follows:
- O ? meat-eating hunter
- A ? grain-eating?farmers
- AB and B ? omnivorous nomads
- The theory is that each group has different levels of digestive enzymes and stomach acidities relating to the kinds of foods that they grew accustomed to eating.
- There is apparently no evidence to support this theory
- Food combining: my course notes observe that this diet plan asserts that protein and carbohydrates should not be eaten together.
- The theory is that starchy foods require a lower stomach acidity for digestion compared with protein-based foods and if they are eaten together this leads to partial breakdown of nutrients, poor absorption and health problems.
- There is apparently no evidence to support this theory
- Meal replacements: my course notes like the idea of meal replacement products (hey, it?s scientific, right!? It must be, it comes in a packet) but ultimately glumly concludes that the products are not ideal because:
- They are expensive
- The tastes are repetitive
- The diets are very low in calories
- Reliance on heavily processed foods is not good long-term healthy eating practice
- Diet clubs: my course notes identify that diet clubs work because of the psychological support provided and notes that on the downside, when this support is removed, the person may regain the weight they have lost.
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Before I even start addressing those criticisms
I was going to go into the detail for each of the above criticisms, explaining why I agree or (more likely) disagree with what my course notes recommend. ?However, I quickly realised that I now have such fundamentally different beliefs about the role of nutrition in a healthy lifestyle that it is almost impossible to go through each item without writing a whole post about it.
If you read my posts about healthy eating guidelines and weight management, you?ve probably already picked these principles up, but just for the record, this is what I believe at the moment:
- There is no connection between the consumption of saturated fat and coronary heart disease (Dr Malcolm Kendrick)
- There is in fact little connection between diet and coronary heart disease (also?Dr Malcolm Kendrick)
- Eating carbohydrates is bad for you unless you are doing a lot of exercise (Robb Wolf)
- On the other hand, protein is pretty good for you and deserves none of the criticism it gets (Dr Lonnie Lowery)
- Stress is a much more significant factor in making people ill from coronary heart disease (Dr Malcolm Kendrick) and metabolic syndrome, leading to obesity and type two diabetes?(Robb Wolf)
- We know far less about the mechanisms by which the body is affected by nutritional protocols than the media like to make us believe (if you don?t believe me, ask someone really clever in a white coat exactly how the liver works).
- If you were to capture a wild animal and keep it in a zoo, you would look to see what it ate in the wild so you could match its feed to what it was accustomed to eating. ?Unless you have been watching too much X-Files and think that we were put here as part of an alien seeding colony, this logic must apply to humans too. ?Assuming that diet has some impact on health, the Paleo Diet is therefore the best nutritional protocol until someone deals with point 6 above.
I am currently unsure about:
- Whether fruits and vegetables are essential for good health, as some research seems to show that they don?t help avoid cancer and I don?t believe they have any effect on coronary heart disease
- Whether fibre is helpful for good health, as some research seems to show that they don?t help avoid cancer?and I don?t believe they have any effect on coronary heart disease
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So where does that leave this post?
Well, in short, I would like to echo Philosoraptor, in saying?
Philosoraptor: not really in a philosophical mood
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You?re a complete lunatic, you know that?
Tell me about it. ?I hear it all the time at work.
Anyway, if we look at the criticisms of the diets listed above, most of them can be eliminated pretty quickly as they refer to fundamentals that I don?t agree with for the reasons listed above. ?However, there are a couple of other criticisms, as follows:
- Low/lower-carbohyrate diets are not sustainable ? ?Melissa McEwan has already demolished this pathetic argument so I won?t belabour these points. ?However, I would note that the American Clinical Journal of Nutrition did do?an article recently that went into this issue in detail and is worth reading if you are interested in the sustainability of our choices. ?For those of you too lazy to click on the link, the answer is that the Paleo Diet is not sustainable for everyone.
- Low/lower-carbohyrate diets are expensive - tell me about it. ?From a purely logical perspective, however, that has absolutely nothing to do with the health benefits of eating low-carb. ?Having said that, if you are interested in eating a better diet more cheaply, there are people around who can help you cut those costs down. ?For those of you too lazy to click on the link, you basically need to man up and eat offal. ?And no, I don?t want to either.
- Low/lower-carbohyrate diets are not suitable for the regular exerciser ? this depends on what your definitions of ?low? carb and ?regular exercise? are. ?My course notes define anything as less than 55% carbohydrates as ?low carb? and ?regular exercise? as miles of endurance exercise. ?This is, obviously, an extreme position. ?For a sensible approach to carbs and endurance exercise, try the Paleo Diet for Athletes or just wait for my post about nutrition for athletes coming up soon.
- There is no evidence to support the blood group diet ? as noted above, the blood group diet is based on the idea that we are all individuals and have different metabolisms based on our genetic ancestry. ?This idea is popular amongst alternative medical practitioners and is a foundation of The Metabolic Typing Diet, which I am going to review shortly. ?To clarify the statement that ?there is no evidence to support the blood group diet?, we should probably say that nobody has ever got a decent grant to look at this within a scientific institution and therefore there aren?t any decent studies on it.
- There is no evidence to support food combining diets ? I think this is a really interesting one but I haven?t got my hands on a good book about it. ?Ranulph Feinnes mentions it in Fit For Life but I haven?t managed to get a whole book on the subject. ?If anyone has a good recommendation, please let me know.
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That?s all folks. ?You may be relieved to hear that my nutrition series is nearly over. ?I just have a post on endurance sports nutrition and the final one is about strength sports nutrition.
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Tags: ? Atkins ? Diets ? Zone
Source: http://www.thegaragegymonline.com/2011/05/17/evaluation-of-popular-diets/
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