Slimmer But Not Healthier
Low carb diets promise (and deliver) rapid weight loss without hunger in the first and most restrictive phase of the diet. That’s why they are popular – everyone likes quick results. Within a few days the scales will show a real difference. But is there a health cost? To date, no low-carbohydrate intervention trials have been of sufficient duration to investigate long-term effects of low-carb diets. But a recent issue of the Lancet reports life-threatening complication that occurred in the short-term. A 40-year old obese woman who strictly followed the low-carb, high-protein Atkins diet for a month ate meat, cheese and salads, took the prescribed Atkins supplements and monitored her urine – all by ‘The Book’. She lost 9 kg in the first month at the end of which she was admitted to New York’s Lenox Hill Hospital intensive care unit with severe ketoacidosis – a condition that occurs when high levels of acids called ketones build up in the blood.
‘Ketones are produced in the liver whenever there is decreased insulin during starvation. A low-carbohydrate diet such as Atkins can lead to ketone production; in fact, the Atkins diet book recommends regular monitoring for ketonuria to confirm adherence to the diet … Our patient had an underlying ketosis caused by the Atkins diet and developed severe ketoacidosis, possibly when her oral intake was compromised from mild pancreatitis or gastroenteritis. This problem may become more recognised because this diet is becoming increasingly popular worldwide,’ say Tsuh-Yin Chen and co- authors.
– Lancet: 2006 (vol 367, pp958)
Commenting in the Lancet, Lyn Steffen and Jennifer Nettleton from the University of Minnesota School of Public Health say: ‘Teaching at-risk individuals how to manage their weight in ways that are healthy and can be maintained for a lifetime is of utmost importance. Traditional and healthy weight-control practices include increasing physical activity and modifying dietary patterns, such as increasing intakes of wholegrain products and fruit and vegetables. Many longitudinal epidemiological studies have shown significantly lower risk of cardiovascular disease, stroke, cancer, and other conditions associated with consumption of fruits, vegetables, and whole-grains; some of these foods are noticeably absent from the menu of low-carbohydrate diets.’ They conclude with the point that: ‘As researchers and clinicians, our most important criterion should be indisputable safety, and low-carbohydrate diets currently fall short of this benchmark.’
– The Lancet: 2006 (vol 367, pp880–1
GI Group: What You Should Know About Low Carb Diets and Ketosis
‘At all times, our bodies need to maintain a minimum threshold level of glucose in the blood to serve the brain and central nervous system,’ write Prof Jennie Brand-Miller, Kaye Foster-Powell and Joanna McMillan-Price in The Low GI Diet. 'If, for some reason, glucose levels fall below this threshold (a very rare state called hypoglycemia), the consequences are severe including trembling, dizziness, nausea, incoherent rambling speech, and lack of coordination. When necessary, the brain will make use of ketones, a byproduct of the breakdown of fat. In people losing weight on a low carb diet, the level of ketones in the blood rises markedly, a state called ketosis, which is taken as a sign of "success". The brain, however, is definitely not at its best using ketones, and mental judgement is impaired. Ketosis is a serious concern in pregnant women. The foetus can be harmed and brain development impaired by high levels of ketones crossing from the mother’s blood via the placenta. Because being overweight is often a cause of infertility, women who are losing weight may fall pregnant unexpectedly. Thus one of the very good reasons we advocate a healthy low GI diet in this context is that there are absolutely no safety concerns for mother or baby. Indeed, there is some evidence that a low GI diet will help mothers control excessive weight gain during pregnancy.' We’ve summarised all the benefits of The Low GI Diet over a low carb diet.
The Low GI Diet
You feel good, you can think straight
You lose fat, not water and muscle
You have energy for exercise
Low in saturated and trans fats
No concerns about safety in children
No concerns about safety in pregnancy
Benefits for mental function
Value-added benefits for long-term health
Low Carb Diets
You may feel headachy and light-headed
You lose fat, water and muscle
Insulin sensitivity is enhanced
Glucose tolerance worsens
You feel lethargic, exercise is tough
Unavoidably high in the bad fats
Immense concerns about safety in children
Immense concerns about safety in pregnancy
Decline in mental performance
Serious doubts about long-term safety
(The Low GI Diet is published by Hachette Livre in Australia and New Zealand, Hodder Mobius in the UK and Marlowe & Company in the US)
Going with the Grain
As we have said before, there are countless reasons to include more whole cereal grains in your diet, but it’s hard to go past the fact that you are getting all the benefits of their vitamins, minerals, protein, dietary fibre and protective anti-oxidants. Studies around the world show that eating plenty of wholegrain cereals reduces the risk of certain types of cancer, heart disease and type 2 diabetes. A new study published in the American Journal of Clinical Nutrition adds to a growing body of evidence. Our results ‘suggest a lower risk of diabetes and heart disease in people who consume diets high in wholegrains’ wrote lead author Majken Jensen from Aarhus University Hospital and Harvard School of Public Health. In this joint Danish-American cross-sectional study, the researchers analysed diet records (assessed by a 131-item food frequency questionnaire) and took blood analyses of 468 men and 473 women to measure intake of whole grains, bran and germ to markers of glycemic control, blood lipids, cholesterol, and inflammation. ‘Compared with participants in the lowest intake group, participants in the highest intake group had lower concentrations of homocysteine, insulin, C-peptide, and leptin. Inverse associations were also observed with total cholesterol, HDL (good) cholesterol, and LDL (bad) cholesterol,’ reported Jensen. No link was observed between the intake of wholegrains and markers of inflammation.
– AJCN (vol. 83 pp 275–83)
GI Group: Don’t make the mistake of equating wholegrains with low GI (indeed most wholegrain breakfast cereals and breads have a high GI). You get double the benefit if your wholegrains are also low GI.
By Bread Alone
Back in July 2005 GI News, we reported on Dr Allison Hodge’s study that found that ‘the simple change from white bread to lower-GI bread within a high carbohydrate diet could reduce the risk of diabetes.’ For many people, just swapping bread type ‘may be a more acceptable dietary change than one requiring a whole new eating pattern,’ concluded the researchers who had followed the diets and health records of more than 36,000 men and women in Australia for four years. A small Swedish cross-over study of seven women with impaired glucose tolerance and a history of gestational diabetes published in the European Journal of Clinical Nutrition highlights the real and immediate value of making the switch. ‘A combination of low GI and a high content of cereal dietary fibre has a beneficial effect on insulin economy in women at risk of developing type 2 diabetes,’ wrote lead author Dr Elin Ostman. For the study, the women were given either a specially baked low GI bread that was rich in dietary fibre or high GI, low fibre bread during two consecutive 3-week periods separated by a 3-week washout period. The results were unanimous. Lowering the GI and increasing dietary fibre ‘improved insulin economy as judged from the fact that all women lowered their insulin responses to the intravenous glucose challenge’ wrote Ostman.
– EJCN (2006) 60, 334–341