Fourth rule - carbohydrates and fats are great
I think most people assume that a low fat diet is a good thing, as is a normal or low Body Mass Index (BMI) and body fact percentile, and certainly in recent years carbohydrates have come to be demonised. But the thing is that like many things, in moderation, fats and carbohydrates are good for you, and they are an essential part of a healthy diet and are cut out at your peril.
Overall the below post is pretty much from a general point of view, and I’ll pick up on sports specific information ie glycogen cycles etc in another post, but to briefly take a sports nutrition perspective – for people with high activity levels, fats and carbohydrates are the two key sources of fuel for the muscle energy cycle. To curb intake of either is asking for a whole bunch of trouble. This is not just a question of fuelling activity, but also fuelling the repair and maintenance of muscle. There is a particular perspective for endurance athletes/people exercising over an extended period of time who may or may not be able to take on enough carbohydrates to be continually able to rely on muscle glycogen for energy. For such endurance athletes the presence of intramuscular triglycerides (fat layers in the muscle) as fuel for exercise is vital to be able to consistently perform at or around the aerobic/anaerobic threshold level ie to have effective endurance. This does of course have to be set against power to weight issues for many if not all sports, but I'm not sure if dietary/intramuscular fat is given sufficient emphasis because low-fat is so in vogue.
A daily recommended dietary balance is:
60-70% Carbohydrates
25-30% Fats
10-15% Protein
for an athlete that moves towards the high carbohydrate end of these percentages.
Why fat is good for you
So here’s an insidious little fact – there is no evidence that a low fat diet is "good" for you - as found by an eight year long study in the US (see http://www.whi.org/findings/dm/dm.php_) Surprising perhaps, well it did make me wonder, given it has been such a focus of so many diets for so long. It was flagged up by my favourite columnist on medical things Margaret McCartney (see www.ft.com/arts/columnists/mccartney), which is worth a read if you have a Financial Times subscription (article is Eat Fat and Be Merry, published February 11, 2006).
Margaret McCartney’s main point is that to follow a low fat diet means cutting out some of the great pleasures in life if you like your food. To me there is additional key point and that is that several key vitamins are fat soluble (A, D, E and K) and will only be found in certain fats and or carbohydrates (see http://www.ext.colostate.edu/pubs/foodnut/09315.html ). Furthermore, some great recipes depend on a heavy dose of fat, and in a life where finding something you want to eat can be tricky, it is a great shame to cut out things unless you really need to.
So how did the low-fat thing come about? Well, the main reason is probably dieting. It is true to say that many of us could do with losing a bit of weight, and the reason why a low fat diet would help you lose weight is that per gram, fat is very calorific and goes straight to the body’s fat deposits if it isn’t used up by activity.
To spell out the blindingly obvious skirted around by most diets – your body weight is very generally speaking, a simple function of (a) how much energy you consume and (b) how energy much you expend, and (c) how efficient your metabolism is getting energy from (a) to (b). Hence naturally skinny people tend to have inefficient or ‘fast’ metabolisms and naturally heavy people efficient or ‘slower’ metabolisms. Hormone imbalances, which can prove difficult to resolve, will unfortunately play hell with metabolic rate amongst other things, and may be a root problem of someone tending to one or other end of the weight spectrum.
Here’s another thing they don’t tell you, dieting encourages your metabolism to become more efficient or ‘slower’ – so over time dieting, particularly severely calorie controlled dieting, can be counter productive (See:
http://www.intelihealth.com/IH/ihtIH/WSIHW000/14220/20705/328226.html?d=dmtContent
http://www.bdaweightwise.com/expert/expert_faq.aspx)
So the simple answer is if you want to lose weight – then eat less calories and run more (ah the delightful simplicity of it - and yes I wish I was lighter, and no I don't find time to run enough :o) ) . Note I didn’t say eat less food or any particular type of food, and I say run because it burns more calories than any other common form of exercise. One of the great fallacies of modern life is the idea that we eat more than we did 50 years ago – which happens to be complete bunkum, the average calorie intake is less than it was during rationing. What has changed is the amount of exercise we take and central heating. So really, if you want to lose weight, the answer isn’t a low fat diet or any other diet for that matter – its to up your exercise, which will also bring you some nice happy hormones e.g. endomorphins and serotonin, and burn out the stress related ones eg adrenaline, cortisol, lactate and assorted chemical nasties – so there’s three good reasons to walk, run or cycle to work.
The subsidiary reason why a low fat intake is recommended is that some fats are ‘bad’. That is to say that certain fats are not burnt as energy so easily and tend to find their way to places in your body where they cause trouble – such as trans-fats and cholesterol. Note a lot of confusing language gets used about cholesterol – you’ve got two levels and the evidence that either is strongly affected by diet is slim, most being produced by the liver (See Magaret McCarthy’s article and http://www.hsph.harvard.edu/nutritionsource/fats.html). But here’s a thing – margarine contains trans-fat (bad news), and once you’ve cooked with many vegetable oils at a high temperature they take on the same structure as animal fat. So the point to this – if you’re cooking and the recipe calls for butter or lard, then use it and rasberries to any impact on cholesterol, because vegetable oil or margarine isn’t necessarily going to be any better for you anyhow.
Carbohydrates
Low-carbohydrate diets have been much in vogue in recent years, but unfortunately there is no cunning way round the basic function of food in minus energy expended means weight gain or loss. The primary reason why people lose weight on Atkins is that they consume less calories (see http://onhealth.webmd.com/script/main/art.asp?articlekey=56061). Carbohydrates as against protein contain more calories per gram, and furthermore, carbohydrates are more tasty. People simply eat less calories on the Akins diet than they otherwise would, there is no magic and no scientific grounding for ‘ketosis’ or many of the other varied claims of low-carbohydrate diets.
But to say that low-carbohydrates don't live up to their claims is not to say that eating white bread all day is necessarily a good idea either. There are two things you need to bear in mind with carbohydrates, firstly the amount of calories per gram, and secondly the rate at which that carbohydrate will become glucose in your blood stream. This is where the Glycemic Index comes in. The GI is a measure of how quickly a food stuff becomes glucose in your blood stream If you need a lot of energy and you need it now – then you want something with a high GI. If you are not going to be taking much exercise, or you won’t be taking exercise for a while, then you want something that will release glucose slowly as you digest it – so you want something with a low GI. Furthermore as a general rule, high GI foods have a high calorie number per gram, where as low GI foods have a lower calorie level per gram. High GI carbohydrates tend to be white, sugary and/or processed – low GI carbohydrates tend to be brown, unprocessed and non-wheat. More on the GI can be found here http://www.glycemicindex.com/.
One thing worth bearing in mind is our ancestry. If you believe the archaeology/anthropology types we are all descended from hunter gatherers. We became smarter at the gathering bit, and learnt to farm and domesticate animals. But nonetheless, our digestive system didn’t really change in all those thousands of years. As a result there is an argument that our digestive system isn’t really geared up to digest high GI grains such as wheat, or dairy produce. Hence body weight issues, food intolerances and Candida infections etc. I like these foods however, and my personal pet view is that I’ll be eating a diet of pulses and vegetables when the moon turns blue. However, its another reason for incorporating low GI grains into your diet – so basmati or brown rice, brown bread and pasta, pulses such as lentils or pearl barley, and couscous is another great low GI alternative.
So to draw to a close – a parting shot on fads and food intolerances – there’s plenty of evidence that most ‘food intolerances’ can be traced back to a low ‘friendly bacteria’ level in your gut, which the various yogurt drinks will help, but best is the bacteria (Bifidobacteria, Lactobactillus etc) in a powder form with a pre-biotic (bacteria food) such as pectin. Available from all good health food stores!
Overall the below post is pretty much from a general point of view, and I’ll pick up on sports specific information ie glycogen cycles etc in another post, but to briefly take a sports nutrition perspective – for people with high activity levels, fats and carbohydrates are the two key sources of fuel for the muscle energy cycle. To curb intake of either is asking for a whole bunch of trouble. This is not just a question of fuelling activity, but also fuelling the repair and maintenance of muscle. There is a particular perspective for endurance athletes/people exercising over an extended period of time who may or may not be able to take on enough carbohydrates to be continually able to rely on muscle glycogen for energy. For such endurance athletes the presence of intramuscular triglycerides (fat layers in the muscle) as fuel for exercise is vital to be able to consistently perform at or around the aerobic/anaerobic threshold level ie to have effective endurance. This does of course have to be set against power to weight issues for many if not all sports, but I'm not sure if dietary/intramuscular fat is given sufficient emphasis because low-fat is so in vogue.
A daily recommended dietary balance is:
60-70% Carbohydrates
25-30% Fats
10-15% Protein
for an athlete that moves towards the high carbohydrate end of these percentages.
Why fat is good for you
So here’s an insidious little fact – there is no evidence that a low fat diet is "good" for you - as found by an eight year long study in the US (see http://www.whi.org/findings/dm/dm.php_) Surprising perhaps, well it did make me wonder, given it has been such a focus of so many diets for so long. It was flagged up by my favourite columnist on medical things Margaret McCartney (see www.ft.com/arts/columnists/mccartney), which is worth a read if you have a Financial Times subscription (article is Eat Fat and Be Merry, published February 11, 2006).
Margaret McCartney’s main point is that to follow a low fat diet means cutting out some of the great pleasures in life if you like your food. To me there is additional key point and that is that several key vitamins are fat soluble (A, D, E and K) and will only be found in certain fats and or carbohydrates (see http://www.ext.colostate.edu/pubs/foodnut/09315.html ). Furthermore, some great recipes depend on a heavy dose of fat, and in a life where finding something you want to eat can be tricky, it is a great shame to cut out things unless you really need to.
So how did the low-fat thing come about? Well, the main reason is probably dieting. It is true to say that many of us could do with losing a bit of weight, and the reason why a low fat diet would help you lose weight is that per gram, fat is very calorific and goes straight to the body’s fat deposits if it isn’t used up by activity.
To spell out the blindingly obvious skirted around by most diets – your body weight is very generally speaking, a simple function of (a) how much energy you consume and (b) how energy much you expend, and (c) how efficient your metabolism is getting energy from (a) to (b). Hence naturally skinny people tend to have inefficient or ‘fast’ metabolisms and naturally heavy people efficient or ‘slower’ metabolisms. Hormone imbalances, which can prove difficult to resolve, will unfortunately play hell with metabolic rate amongst other things, and may be a root problem of someone tending to one or other end of the weight spectrum.
Here’s another thing they don’t tell you, dieting encourages your metabolism to become more efficient or ‘slower’ – so over time dieting, particularly severely calorie controlled dieting, can be counter productive (See:
http://www.intelihealth.com/IH/ihtIH/WSIHW000/14220/20705/328226.html?d=dmtContent
http://www.bdaweightwise.com/expert/expert_faq.aspx)
So the simple answer is if you want to lose weight – then eat less calories and run more (ah the delightful simplicity of it - and yes I wish I was lighter, and no I don't find time to run enough :o) ) . Note I didn’t say eat less food or any particular type of food, and I say run because it burns more calories than any other common form of exercise. One of the great fallacies of modern life is the idea that we eat more than we did 50 years ago – which happens to be complete bunkum, the average calorie intake is less than it was during rationing. What has changed is the amount of exercise we take and central heating. So really, if you want to lose weight, the answer isn’t a low fat diet or any other diet for that matter – its to up your exercise, which will also bring you some nice happy hormones e.g. endomorphins and serotonin, and burn out the stress related ones eg adrenaline, cortisol, lactate and assorted chemical nasties – so there’s three good reasons to walk, run or cycle to work.
The subsidiary reason why a low fat intake is recommended is that some fats are ‘bad’. That is to say that certain fats are not burnt as energy so easily and tend to find their way to places in your body where they cause trouble – such as trans-fats and cholesterol. Note a lot of confusing language gets used about cholesterol – you’ve got two levels and the evidence that either is strongly affected by diet is slim, most being produced by the liver (See Magaret McCarthy’s article and http://www.hsph.harvard.edu/nutritionsource/fats.html). But here’s a thing – margarine contains trans-fat (bad news), and once you’ve cooked with many vegetable oils at a high temperature they take on the same structure as animal fat. So the point to this – if you’re cooking and the recipe calls for butter or lard, then use it and rasberries to any impact on cholesterol, because vegetable oil or margarine isn’t necessarily going to be any better for you anyhow.
Carbohydrates
Low-carbohydrate diets have been much in vogue in recent years, but unfortunately there is no cunning way round the basic function of food in minus energy expended means weight gain or loss. The primary reason why people lose weight on Atkins is that they consume less calories (see http://onhealth.webmd.com/script/main/art.asp?articlekey=56061). Carbohydrates as against protein contain more calories per gram, and furthermore, carbohydrates are more tasty. People simply eat less calories on the Akins diet than they otherwise would, there is no magic and no scientific grounding for ‘ketosis’ or many of the other varied claims of low-carbohydrate diets.
But to say that low-carbohydrates don't live up to their claims is not to say that eating white bread all day is necessarily a good idea either. There are two things you need to bear in mind with carbohydrates, firstly the amount of calories per gram, and secondly the rate at which that carbohydrate will become glucose in your blood stream. This is where the Glycemic Index comes in. The GI is a measure of how quickly a food stuff becomes glucose in your blood stream If you need a lot of energy and you need it now – then you want something with a high GI. If you are not going to be taking much exercise, or you won’t be taking exercise for a while, then you want something that will release glucose slowly as you digest it – so you want something with a low GI. Furthermore as a general rule, high GI foods have a high calorie number per gram, where as low GI foods have a lower calorie level per gram. High GI carbohydrates tend to be white, sugary and/or processed – low GI carbohydrates tend to be brown, unprocessed and non-wheat. More on the GI can be found here http://www.glycemicindex.com/.
One thing worth bearing in mind is our ancestry. If you believe the archaeology/anthropology types we are all descended from hunter gatherers. We became smarter at the gathering bit, and learnt to farm and domesticate animals. But nonetheless, our digestive system didn’t really change in all those thousands of years. As a result there is an argument that our digestive system isn’t really geared up to digest high GI grains such as wheat, or dairy produce. Hence body weight issues, food intolerances and Candida infections etc. I like these foods however, and my personal pet view is that I’ll be eating a diet of pulses and vegetables when the moon turns blue. However, its another reason for incorporating low GI grains into your diet – so basmati or brown rice, brown bread and pasta, pulses such as lentils or pearl barley, and couscous is another great low GI alternative.
So to draw to a close – a parting shot on fads and food intolerances – there’s plenty of evidence that most ‘food intolerances’ can be traced back to a low ‘friendly bacteria’ level in your gut, which the various yogurt drinks will help, but best is the bacteria (Bifidobacteria, Lactobactillus etc) in a powder form with a pre-biotic (bacteria food) such as pectin. Available from all good health food stores!
posted by Ems at 8:21 AM
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