Carbohydrate, not fat, consumption is linked with increased risk of metabolic syndrome

In recent years there has been increasing awareness regarding a condition known a ‘metabolic syndrome’. While its precise definition varies a bit, the main feature of metabolic syndrome is excess weight around the midriff (abdominal obesity), coupled with other unwanted findings such as raised levels of sugar and/or blood fats known as triglycerides, raised blood pressure, and low levels of ‘healthy’ HDL cholesterol. Those suffering from metabolic syndrome have been found to be at significantly enhanced risk of conditions such as type 2 diabetes and heart disease.

What causes metabolic syndrome has been a subject of some debate, and the focus here has naturally been on diet and exercise. Traditionally, as far as nutrition is concerned, the emphasis has been (rather predictably) on fat. Basically, the concept here is that eating a lot of fat is most likely to make us fat, and therefore increase our risk of the excess weight that is the hallmark of metabolic syndrome.

However, this proposed mechanism does not quite make sense when one considers the fact that a key biochemical imbalance in metabolic syndrome is raised levels of the hormone insulin. Insulin is primarily secreted in response to rising levels of sugar in the bloodstream, which comes, essentially, from the eating of either sugar and/or starch. Eating fat, on the other hand, does not cause insulin levels to rise. Despite these plain biochemical facts, individuals with metabolic syndrome are often advised to eat a low-fat, high-carb diet.

In a study published recently in the Journal of the American Geriatrics Society, researchers based in London, UK, went about assessing risk factors, including diet, for metabolic syndrome in a group of men aged 60-79 years [1].

Two factors associated with an enhanced risk of metabolic syndrome included physical inactivity and smoking.

When the researchers analysed the dietary data they found that fat intake was NOT associated with metabolic syndrome risk.

However, a high-carbohydrate diet was found to be associated with increased risk of metabolic syndrome. In this study, a high-carbohydrate diet was defined as one in which more than 57 per cent of calories come from carbohydrate. It should perhaps be noted that we are very often encouraged to ensure that 60 per cent or more of our calories are carb-based.

A study of this nature (known as an ‘epidemiological’ study) cannot prove that eating an excess of carbohydrate causes metabolic syndrome. The fact that carbs cause insulin secretion means there is a plausible biological mechanism which could explain this association.

This study also assessed the impact of lifestyle modification on metabolic syndrome risk. Compared to individuals whose weight did not change, those who lost weight in the preceding 2-4 years had about half the risk of metabolic syndrome. What this study suggests is that lifestyle modification is likely to protect against metabolic syndrome, even relatively late in life.

Those wanting to prevent or even reverse metabolic syndrome might look to take some regular activity. Personally, I recommend daily walking. In addition, it would seem sensible for individuals to control their intake of carbohydrates that tend to boost blood sugar and insulin levels. Foods with added sugar will generally do this, as will starchy carbohydrates such as bread (even wholemeal bread), potato, rice, and many breakfast cereals.

In finding a link between carbohydrate intake and metabolic syndrome this recent study has merely helped to confirm what is blindingly obvious to anyone with even a rudimentary knowledge of biochemistry. My hope, though, is that it might help ease the grip of doctors and scientists who seem to cling tenaciously to the notion that metabolic syndrome and related ills (including diabetes) are down to fat.

References:

1. Wannamethee SG, et al. Modifiable lifestyle factors and the metabolic syndrome in older men: effects of lifestyle changes. Journal of the American Geriatrics Society. 2006;54(12):1909-14

12 Responses to Carbohydrate, not fat, consumption is linked with increased risk of metabolic syndrome

  1. Varadachary 5 January 2007 at 3:08 pm #

    I fear this is too simplistic. Just as there are wrong fats there wrong carbs too.
    I had a heart attack 9 years ago. I was diagnosed as having unstable angina; and was advised to undergo bypass surgery. I refused and went on –to put it briefly–a somewhat low fat(no transfat or butter, a little ghee occasionally, very little fried food and virgin sesame or olive oil in raw form)limited but sufficient complex carbohydrates(very important), minimum req’d veg. protein to ensure Folate and a diet made up ofof 2/3 rds veggies and fruits; And not more than 1200 calories(critical, a I am small)). I have an active life( after leaving the higher civil service). In other words a complex carb/low fat diet will work. The problem with the western diet(and indian diet is too much refined food, heated oil and sugar.Any useful study must look at the breakdown of the major food categories and not just carbs or fat!
    v

  2. Dr John Briffa 5 January 2007 at 3:40 pm #

    You’re right, not all carbs are bad. I generally endorse fruit and vegetables, but what is the rationale for the ‘complex carbs’ you say are “very important”? I did, I think, draw this distinction in the blog by specifically mentioning the carbs that tend to be disruptive for blood sugar and insulin.

    I also think it’s good that you are avoiding trans fat, but have never seen any convincing evidence that eating butter (saturated and monounsaturated fat) contributes to heart disease risk. If you have some evidence to the contrary, please supply it.

    And finally, I’m not sure you can say with such assurance that a high-carb/low-fat diet “WILL work” (emphasis is mine): I am not dismissing your experience, but it’s important to take a wider view if we are to get a fuller picture. ‘Case studies’ such as yours are a good place to start in the absence of available evidence. However, if we DO have relevant science, I say let’s use it.

  3. George Steele MD 5 January 2007 at 7:09 pm #

    I have suggested my patients consume what I refer to as the “Mediterranean Hunter-Gatherer Diet”, which is heavy in dark green vegetables, healthy oils (fish, olive), nuts, berries, meat/fish/poultry (plus/minus a little alcohol if desired), in descending amounts. No pasta, bread, potatoes or rice (which I refer to as dog-food filler). Most of us consume too many calories anyway, so why add fillers? Limit the fruit to berries if you are trying to lose weight (otherwise the fruit is mostly sugar.
    I have created an educational website for my patients to help them with this (www.georgesteelemd.com, which is completely no-profit, I can tell you!).

    Cheers, George

  4. Dr John Briffa 5 January 2007 at 7:28 pm #

    I like the sound of this diet A LOT. Cheers indeed, George!

  5. Marlene Aung 6 January 2007 at 12:42 am #

    Dear Dr. Briffa,

    I had a blood test recently, where it showed a higher level of trycleridi than normal, I would like to ask you, if there could also be a possible conncection of this metabolic syndrome with high cholesterol, though I do have a healthy diet, no cakes, no biscuits or chocolate, I eat lots of fruit, chicken and fish, rice, whole grain bread, no pasta
    Please could you tell me what else I could do to lower these trycleridi.
    Thank you

  6. Neil 6 January 2007 at 1:42 am #

    Me too. This is what the British Diabetic Association and British Heart Foundation should be advocating! Fat chance of that.

  7. Brian Abbott 7 January 2007 at 12:04 am #

    The reason why we have had such a heavy emphasis on carbohydrates, for instance in the ‘Food Pyramid, ‘ is that taking some cheap carbohydrate like corn, wheat, potato,or rice, and adding some colour or sugar or partially hydrogenated vegetable oil, or some other cheap ingredent makes a huge profit for food manufacturers. Governments don’t like to interfere too much with the activies of businessmen and certainby don’t want to introduce any rules that might reduce their profits of food manufacturers and dividends to their share holders. So they bring the representatives of the food manufacturing industry onto committies that decide what food should be recommended as healthy. The problem of obesity will never be solved until the only brief of agencies like the FSA is to ensure all food consumed by the public is beneficial, without having to take the interests of manufacturers and farmers into consideration at all.

  8. Julie 7 January 2007 at 7:27 pm #

    I could not agree more! And I love your articles, and just wish the media / government / NHS would take notice and stop going on about how unhealthy fat is. I am 25 and up until 5 years ago I was 17 stone with insulin resistance / metabolic syndrome, along with polycystic ovary syndrome, and covered in acne, lack of periods, extreme mood swings & tiredness, and was heading for full diabetes and alot more health problems. I ate very little fat, thinking I was healthy with cereal, bread, potatoes, rice, pasta, low-fat margarine, skimmed milk, fruit, etc. Once I was diagnosed I tried low-carbing, eating natural animal & plant-based food, with high saturated & monounsatured fats, and moderate/normal protein. I am now 11 stone and have vastly improved my overall health just through changing my eating habits. Good luck to anyone trying the same as its worth it, and you begin to realise how processed and horrible all that packaged food is!

  9. Kate 8 January 2007 at 10:16 pm #

    Very, very important information. I had a cholesterol test and my triglycerides were ten times more than the upper limit. I thought that if I followed a very low-fat diet (the Ornish diet) then I would be fine. Six months later, the cholesterol test was just as bad and my GP prescribed Zoccor. I found that the statin drugs only worked for around six weeks and this was quite worrying.
    I moved house and my new GP recommended the ‘Atkins’ diet and all my dietary problems improved within a week, no more heartburn, my triglycerides and LDL improved and my HDL actually rose.
    I have also discovered that a hypothyroid condition also contributes towards metabolic syndrome. I take thyroxine now and am very careful about the GI content of foods.
    My days of regular cholesterol tests are past now as I no longer have private healthcare, but I am confident that I am doing what is right for me.
    The only problem is, that I have MS now. It is difficult to ignore the dietary advice for people with MS – a diet similar to the Ornish no-saturated fat approach. The ‘Best Bet’ diet is a classic story of dietary brain-washing. ‘Eat this diet and you can control your MS’.
    Hmm. No thanks. For me, it would be ‘eat this diet and watch type 2 diabetes take over your body’.

    Keep up the good work, Dr Briffa. I just wish that dieticians and nutritional experts could see the sense.

  10. MAC 7 January 2008 at 6:59 am #

    I don’t know if Gary Taubes’ “Good Calories Bad Calories” has been published in the UK as yet but if you read it very carefully he goes through a lot of the research that is now more than 50 years old making the case for why carbs and not fat are at the root of metabolic syndrome.

  11. Doctor B 25 November 2008 at 1:58 am #

    ‘Basically, the concept here is that eating a lot of fat is most likely to make us fat, and therefore increase our risk of the excess weight that is the hallmark of metabolic syndrome.’

    I’m sorry, but who as ever made the above statement that alot of fat will make us fat? I’ve never heard this before. What I have heard is that alot of calories along with inactivity will lead to excessively stored fat and ultimately to metabolic syndrome. . You take in more than your body utilizes, and it will be stored. Now that is rudimentary biochemistry. So it’s not really about low carb or low fat. It’s moderation and balance. Just like fat in the 70s and 80s, carbs have now become the enemy.

Trackbacks/Pingbacks

  1. I’ll have what she’s having. | primalmeded - 26 April 2011

    [...] And since now we hopefully agree that our weight is regulated by hormones, has anything changed in our bodies on hormonal level? Yes. Let me introduce you to insulin resistance, the key player in metabolic syndrome. Think of it as a link between overweight and diabetes. If you remember, insulin’s job is to let glucose into the muscle, liver and fat cells. Insulin resistance means just that: cells, especially liver and muscle cells, stop responding to insulin and do not let any more glucose inside. As a result a couple of things happen. Blood glucose levels go up, firstly because of peripheral resistance (muscle cells close their doors to glucose), secondly because liver cells fail to detect the rising blood sugar and do not down regulate their own glucose production. Double whammy means more glucose floating around your system (=hyperglycaemia). Pancreas try fight the flood of glucose by releasing even more insulin (=hyperinsulinaemia). Does this sound like perfect conditions for putting on some extra fat? (I’ll discuss the causes of insulin resistance another time, but you can be sure that carbs will not be an innocent bystander). [...]

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