Diet and nutrition

Sleep starved dieters might be thwarting their fat loss plans

October 15, 2010 No Comments

A small study from the United States has suggested that getting too little sleep might prevent dieters from losing as much body fat as they would have had they slept properly.

When individuals slept for five and a half hours a night, they lost half as much body fat as when they were allowed to sleep for eight and a half hours a night and 50% more lean body mass. These results highlight the importance of human sleep for the loss of body fat when dieting.

Many people today are overweight or obese – the prevalence of obesity in England is thought to be 33% and 28% for men and women, respectively. Furthermore, 42% of men and 30% of women are expected to be overweight in 2010.

Losing weight by dieting is one sensible way of addressing this epidemic and thus reducing the poor health associated with being overweight or obese. However, emerging data suggest that insufficient sleep might affect the response of our hormones to reduced food intake and negatively influence the metabolic effects of eating less.

A total of 12 overweight, non-smoking, middle aged (range 35 to 49 years) individuals were enrolled in this study, of whom 10 (three women and seven men) took part. Alarmingly, one woman was withdrawn from the study because the combination of calorie and sleep restriction caused heart palpitations, whereas another woman dropped out for reasons unrelated to the study.

Participants spent two 14 day stints in the University of Chicago sleep laboratory, with three months inbetween to recover. To start with six were allowed 8.5 hours of sleep a night, while the other four were only allowed 5.5 hours. Then the groups switched over so that those who had been enjoying 8.5 hours a sleep a night were only allowed 5.5, and vice versa.

Before and after each study period, fasting body weight, adiposity, fat-free body mass, and the levels of various hormones related to metabolism were measured. Participants ate their normal diet during each 14-day intervention period, but its calorie content was 10% than what they would usually eat.

Interestingly, both the sleep situations – 5.5 hours a night and 8.5 hours a night – were associated with about 3kg of weight loss. However, when people were sleeping 8.5 hours a night, roughly half of the weight loss (1.4kg) was down to reduction in fat, compared with only about a quarter (0.6kg) when people had 5.5 hours of sleep (55% less fat loss in the sleep reduction group). When sleep was restricted to 5.5 hours a night, people lost more fat-free body mass instead, which is largely made up of muscle and water (60% increase in fat-free weight loss).

People were also hungrier and had higher concentrations of the hormone ghrelin when they only got 5.5 hours of sleep a night. Ghrelin has been shown to reduce energy expenditure, stimulate hunger and food intake, and promote retention of fat. People also had a lower resting metabolic rate during the 5.5 hours a night study period – all the better to ensure the finite amount of energy available would stretch to cover the longer waking hours.

The authors suggest that in the sleep deprived state, the body concentrates increasing amounts glucose in fat tissue to support the more prolonged energy needs of the glucose hungry brain. When energy intake is reduced in this situation, the body “holds on” to fat stores to make sure enough energy is available for the drawn out waking hours and instead uses energy stored in muscle – the fat-free body mass.

The authors also suggest that people trying to lose weight who don’t get enough sleep could find it harder to stick to their diet and might be more susceptible to piling on the pounds if they do slack off. “The enhanced metabolic, neuroendocrine, and behavioral compensation in the form of increased hunger and reduced energy expenditure that develop in response to combined caloric and sleep restriction can disrupt adherence to a lower-energy diet and promote efficient weight regain once it is discontinued,” they write.

Writing in an editorial on the topic, Shahrad Taheri of the University of Birmingham, UK, and Emmanuel Mignot from Stanford Sleep Medicine Center in California suggest that sleep should be included as part of the lifestyle package for weight loss, which traditionally has focused on diet and exercise instead.

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Nedeltcheva AV et al. (2010) Insufficient sleep undermines dietary efforts to reduce adiposity. Annals of Internal Medicine 153 (7): 435-41. PMID: 20921542

Cardiovascular medicine, Diet and nutrition

Obese children are at high risk of death before middle age

February 19, 2010 1 Comment

A study published in the New England Journal of Medicine has found that children who were obese were almost twice as likely to die before 55 years of age than those who were not obese. Moreover, children whose weight was in the top 25% out of nearly 5,000 kids were 2.3 times more likely to die from diseases before middle age than those whose weight fell in the bottom 25%.

The authors of this big, long study looked at body mass index (BMI; a measure of weight that takes into account a person’s height) and risk factors for cardiovascular disease in 4,857 children aged 5-19 years who lived on an American Indian reserve in Arizona.

BMI and markers of cardiovascular disease were measured in all children when the study started in 1966 or after. The participants were then followed up until their death, their 55th birthday, or the end of 2003, whichever came first.

A total of 559 (11.5%) participants died before the age of 55, 166 (3.4%) of whom died from a disease or from self inflicted injury such as alcohol or drug abuse – so-called “endogenous causes.”

Children whose BMI fell within the top 25% of all those in the study were 2.3 times more likely to die from endogenous causes before the age of 55 than those whose BMI was in the lowest 25%. In fact, each one unit increase in BMI increased the risk of early death from endogenous causes by 40%. This relationship persisted but at a slightly lower level once factors like cholesterol level and blood pressure were taken into account.

The authors then looked specifically at the 1394 (28.7%) children who were obese – those whose BMI fell in the top 5% on growth charts from governmental public health body the Centers for Disease Control and Prevention. Compared with non-obese children, these kids were 31% more likely to die before they reached 55.

Children with high blood glucose levels – a sign that diabetes might be on the horizon – were at 73% higher risk of dying early, whereas those with hypertension were at 57% higher risk. This link prompted the authors to say that the link between obesity and premature death “may be partially mediated by the development of glucose intolerance and hypertension in childhood.”

Childhood cholesterol level and blood pressure, however, had no effect on the risk of premature death from endogenous causes.

Speaking to the New York Times, senior author Helen Looker said, “This suggests that obesity in children, even prepubescent children, may have very serious long-term health effects through midlife — that there is something serious being set in motion by obesity at early ages. We all expect to get beyond 55 these days.”

American Indians were studied because childhood obesity has been common for decades in this ethnic group. The prevalence of obesity in young Arizona Pima Indians in the 1960s, when this study was initiated, was similar to that seen in Hispanic and African American children today, so hopefully the results from this long study should be generalisable to kids today.

In a linked editorial, Edward W Gregg of the Centres for Disease Control and Prevention pointed out: “Since the trends with respect to obesity and diabetes among the Pima Indians have been a reliable harbinger for trends in the rest of the U.S. population during recent decades, the present study should intensify the debate about whether interventions that are initiated during childhood and young adulthood can affect our broader diabetes epidemic.”

Furthermore, in a previous study the same authors found that BMI correlated closely with total body fat – adiposity – and that adiposity in turn correlated with cardiovascular risk factors. By extension, the link between BMI and early death in this study suggests that actual body fat is linked with early death.

This is important because BMI is an imperfect measure of weight – for example, some very muscular people might be heavy for their height and thus have a high BMI – thus despite the study results weight might not genuinely be associated with early death. On the other hand, high adiposity – “fatness” – is a more indicative of an unhealthy weight.

“Childhood obesity is becoming increasingly prevalent around the globe. Our observations, combined with those of other investigators, suggest that failure to reverse this trend may have wide-reaching consequences for the quality of life and longevity,” conclude the study authors.

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Franks P et al. (2010) Childhood Obesity, Other Cardiovascular Risk Factors, and Premature Death. New England Journal of Medicine 362 (6): 485-493. DOI: 10.1056/NEJMoa0904130

Cardiovascular medicine, Diet and nutrition, Public health

Reducing dietary salt by half a teaspoon could save 92,000 lives a year

February 5, 2010 1 Comment

A Californian population based study has found that if everyone in the US reduced their daily salt intake by 3 grams – half a teaspoon – the annual number of deaths could be slashed by up to 92,000. In addition, the number of new people who get cardiovascular disease each year could drop by up to 120,000 – that’s equivalent to the population of Cambridge!

In fact, cutting dietary salt intake by as little as 1 gram a day could reduce the number of deaths from any cause by 15,000 to 32,000 and the number of new cases of cardiovascular disease by 20,000 to 40,000.

US regulations recommend that people consume less than 5.8 g of salt a day, yet the average American man gets through almost double that – 10.4 g of salt daily. This is bad news – high salt intake is associated with an increased risk of stroke and cardiovascular disease.

In this study, published in the New England Journal of Medicine, the authors used computer modelling to simulate heart disease and stroke in US adults aged 35-84 years.

They found that a population wide reduction in dietary salt of 3 g per day could potentially reduce the annual number of cases of cardiovascular disease by 60,000 to 120,000, stroke by 32,000 to 66,000, and heart attack by 54,000 to 99,000. The annual number of deaths from any cause could be cut by by 44,000 to 92,000.

Even a modest reduction of 1 g of salt per day could cut the yearly rates of cardiovascular disease, stroke, and heart attack by at least 20,000, 18,000, and 11,000, respectively. “It was a surprise to see the magnitude of the impact on the population, given the small reductions in salt that we were modeling,” Kirsten Bibbins-Domingo, lead author of the study, told Science Daily.

The effects seemed greater in black people – a population with high rates of hypertension and cardiovascular disease – and women would benefit in particular from a reduction in stroke incidence. The number of events related to cardiovascular disease – such as heart attack – would drop in older adults, whereas young people would benefit from lower overall mortality rates.

The public health benefits of a drop in salt intake of 3 g a day would be equivalent to half of all smokers quitting or a 5% reduction in body fat among obese adults, and would save $10 billion to $24 billion a year in healthcare costs.

“Reducing dietary salt is one of those rare interventions that has a huge health benefit and actually saves large amounts of money,” said senior author Lee Goldman. “At a time when so much public debate has focused on the costs of health care for the sick, here is a simple remedy, already proven to be feasible in other countries.”

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Bibbins-Domingo K et al. (2010) Projected Effect of Dietary Salt Reductions on Future Cardiovascular Disease. New England Journal of Medicine DOI: 10.1056/NEJMoa0907355

Diet and nutrition

Sacre bleu! French diet doesn’t meet nutrient recommendations

October 7, 2009 2 Comments

French food is famous around the world. From the haute cuisine espoused by cordon bleu and the Michelin Guide to weird and wonderful dishes like frogs legs, the French are passionate about cooking and what they eat.

However, a study published recently in the Journal of Nutrition has found that the diet consumed by the majority of French adults doesn’t meet nutrition recommendations. Only 22% of adults could meet dietary requirements by fine tuning what they already ate, whereas the remaining 78% of French adults would need to expand their diet.

The authors of this study used modelling techniques to create diet plans based on an individual’s “habitual food repertoire” – i.e. the kinds of foods they regularly consumed. The idea of this approach was to calculate a diet plan that met nutritional recommendations without deviating much from the foods the individual already liked to eat.

More than a thousand French adults who were participating in the French national food consumption study provided seven day food diaries. The authors then tried to design for each individual a diet plan that met 30 different food recommendations by using the foods in their weekly food repertoire. The designed diets varied according to the individual’s gender, age and observed nutrient intake levels.

The authors found that they could only put together diets that met all 30 recommendations for 22% of adults – i.e. only a fifth of the sample had diets that could be tweaked to be nutritionally sound on the basis of how foods were combined or how big portion sizes were. These individuals consumed more energy and more fruit and vegetables than those whose food repertoire couldn’t be juggled to meet requirements.

On the other hand, it was mathematically impossible to design a nutritionally adequate diet for the remaining 78% without extending the range of foods they ate. The main problem among participants with unsatisfactory diets was that their favourite foods didn’t contain enough vitamin D, although their diet plans also couldn’t be manipulated to within maximum sodium levels or minimum magnesium recommendations.

Unsurprisingly, feasible diets could be put together for every participant when the food options were not limited to the individual’s food repertoire.

This study suggests not only that the diets of most French adults aren’t anywhere near meeting nutrition requirements, but also that considerable changes will need to be made to the foods eaten in order to meet a healthy diet. Maybe French food isn’t all it’s cracked up to be after all…

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Maillot M et al. (2009) To Meet Nutrient Recommendations, Most French Adults Need to Expand Their Habitual Food Repertoire. Journal of Nutrition 139 (9): 1721-1727. DOI: 10.3945/jn.109.107318

Diet and nutrition

Red meat consumption increases the risk of early death

March 24, 2009 No Comments

Red meat Results from a huge study published in Archives of Internal Medicine have shown that consumption of a high level of red and processed meat is associated with a raised risk of early death.

Men who ate the most red meat – roughly equivalent to a quarter pounder burger a day – were 31% more likely to die within 10 years than men who ate less red meat. Women eating similarly high quantities of red meat were 36% more likely to die than those who ate less red meat.

This prospective study assessed half a million people aged 50 to 71 years from six US states (California, Florida, Louisiana, New Jersey, North Carolina and Pennsylvania) and two metropolitan areas (Atlanta, Georgia and Detroit, Michigan).

A bumper 124-item food frequency questionnaire was used to collect information on what sort of foods and drinks had been consumed over the previous 12 months, and meat intake was calculated using this information and portion size data. Red meat included all types of beef and pork, white meat comprised chicken, turkey and fish and processed meat included bacon, red meat sausage, poultry sausage, luncheon meats, cold cuts, ham and hotdogs.

Participants were then followed up for 10 years, during which 47,976 men and 23,276 women died. Men and women who ate the highest amounts of red meat on – average 66-68 grams per 1,000 calories – were more likely to die during the 10-year follow up than those who ate much smaller quantities of red meat – less than 10 grams per 1,000 calories.

In addition, men who ate the most red meat were 22% more likely to die of cancer and 27% more likely to die of heart disease than men who ate little red meat, whereas the corresponding figures for women were 20% and 50%.

High processed meat intake – 16-19 grams per 1,000 calories – also increased the risk of total, cancer and cardiovascular disease mortality. On the other hand, total mortality and cancer mortality decreased as white meat intake increased.

If red meat eaters changed their diet and cut the red meat in favour of white meat, 11% of deaths in men and 16% of deaths in women could be prevented.

The researchers had adjusted their analyses to take into account participants’ age, weight, smoking history and total food intake, increasing the chance that the higher mortality rate among red and processed meat eaters was in fact down to their diet and not the effect of another lifestyle factor.

However, participants who ate a lot of red meat were more likely a current smoker, have a higher body mass index and have a higher daily intake of energy, total fat and saturated fat than people who ate less red meat, and they tended to have lower physical activity levels and lower fruit, vegetable and fiber intakes. As the authors acknowledge, “It’s unlikely we’re ever going to feed people meat and see what happens”.

The study authors suggest that the effect of red meat on mortality could be down to the carcinogens formed during the cooking of red meat. In addition, high intakes of red and processed meat raise blood pressure and thus cardiovascular risk, although the mechanism of this effect is unknown.

In an editorial that accompanies this article, Barry M Popkin, professor of nutrition at the University of North Carolina, Chapel Hill and head of the Division of Nutrition Epidemiology, points out that a high-protein, low-carbohydrate diet is just as healthy as a low-fat, high–carbohydrate diet, “[t]hus, the consensus is not that we should all become vegans or vegetarians”. Instead, he suggests, we should dramatically cut down our intake of processed meats and try to limit our consumption of meat overall.

Prof Popkin also highlights how cutting down meat intake could forestall the impending food crisis brewing as developing countries like China and India adopt a protein-heavy Western diet.

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Sinha R et al. (2009) Meat Intake and Mortality: A Prospective Study of Over Half a Million People. Arch Intern Med 169 (6): 562-571. Full text online: here

Cancer, Diet and nutrition

Got breast cancer? Get to your greengrocers!

February 24, 2009 No Comments

Fruit & Veg Fresh fruit and vegetables can inhibit the growth of breast cancer tumors and reduce the risk of death in women who already have breast cancer, say two new studies.

The first study is one of several on the effects of fresh apple extracts in rats. Whole apple extracts have strong antiproliferative and antioxidant activities, thought to be a result of the combination of phytochemicals in the fruit.

This study found that giving rats with mammary tumors a dosage of apple extracts equivalent to one apple a day in humans seriously curtailed the likelihood of tumor growth. In total, only 57% of rats fed low doses of apple extracts experienced rapid tumor growth over the 24-week study compared with 81% of control animals, who received no apple extracts whatsoever.

Strikingly, only 23% of the rats fed high doses of apple extracts showed signs of tumor proliferation. Scaled up, a human would need to consume six apples a day to benefit from this protective effect.

Rui Hai Liu, Cornell associate professor of food science and one of the study’s authors, said, “We not only observed that the treated animals had fewer tumors, but the tumors were smaller, less malignant and grew more slowly compared with the tumors in the untreated rats.”

A second study of 1,901 women with early-stage breast cancer found that a healthy diet of fruit, vegetables, whole grains, and poultry reduced the risk of death from any cause.

The risk of death in women who stuck rigidly to a ‘prudent’ diet was almost 50% lower than that in women who paid less attention to what they ate. On the other hand, the risk of death in women who ate a Western diet comprising a high intake of red and processed meats and refined grains was much higher than in less unhealthy women. These observations were generally not modified by physical activity, being overweight, or smoking.

Interestingly, neither dietary pattern was associated with risk of breast cancer recurrence or death from breast cancer.

The authors conclude that “women diagnosed with early-stage breast cancer might improve overall prognosis and survival by adopting more healthful dietary patterns.”

Diet and nutrition, Nephrology

Make it a DIET coke break, for the sake of your kidneys

February 11, 2009 8 Comments

Diet coke break New research published in PLoS One has shown that drinking two or more fizzy drinks a day can double a woman’s chance of developing signs of kidney disease – but only if she drinks full-sugar sodas.

David A Shoham and colleagues studied data from more than 9,000 individuals in the population-based National Health and Nutrition Examination Survey (1999–2004). They found that women who drank two or more cans of soda per day were nearly twice as likely to develop early signs of kidney disease compared with women who consumed fewer sugary soft drinks. Women who drank diet soda were not at increased risk of kidney disease, nor were men.

The rise in diabetes, obesity and kidney disease in the US has paralleled an increase in the use of high fructose corn syrup in American food. High fructose corn syrup is used in particular as a cheap way to sweeten fizzy drinks; thus, the authors investigated whether consumption of soft drinks is associated with albuminuria, a sensitive marker of early kidney damage.

In total, 11% of the sample population were found to have albumnuria, and 17% of the study group drank two or more sugary soft drinks per day. Individuals who drank more than two fizzy drinks a day were 40% more likely to have albuminuria than were participants with a more moderate intake of soda. Consumption of diet soda, however, was not associated with albuminura.

When the authors broke down their results by gender, they found that women who reported drinking two or more sodas in the previous 24 hours were 1.86 times more likely to have albuminuria than were women who drank less soda. Drinking fizzy drinks had no significant effect on the risk of albuminuria in men.

An analysis of type of soda showed that consumption of sugary non-colas was most strongly linked with albuminuria, whereas sugary cola and diet cola and non-cola drinks showed no such association.

The authors conclude that the correlation between drinking sugary sodas and albuminuria indicates that high fructose corn syrup is in part responsible for the increase in kidney disease in the US. According to the National Kidney Foundation, about 26 million American adults have chronic kidney disease.

Dr Shoham, however, has said. “I don’t think there is anything demonic about high fructose corn syrup per se … People are consuming too much sugar. The problem with high fructose corn syrup is that it contributes to over consumption. It’s cheap, it has a long shelf life and it allows you to buy a case of soda for less than $10.”
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Shoham DA et al. (2008) Sugary Soda Consumption and Albuminuria: Results from the National Health and Nutrition Examination Survey, 1999–2004 PLoS ONE 3 (10) DOI: 10.1371/journal.pone.0003431

Children, Diet and nutrition, Events, Public health

Government to tackle obesity with Change4Life campaign

January 2, 2009 2 Comments

I recently blogged about the alarming rates of obesity among children in England, with one in four 4-5 year old children and one in three 10-11 year olds in this country obese or overweight. The Foresight report, published in 2007, ominously predicts that by 2050 90% of British children will be overweight or obese.

The British Government has now responded to this issue by launching a huge campaign to persuade the population to switch to a healthier lifestyle. The Change4Life strategy will promote the message “eat well, move more, live longer” on TV, in the press, on billboards and online initially for 3 months, and will continue over 3 years. The initiative will be supported by £200m of advertising and marketing donated by food companies such as Tesco, Mars, Nestlé and Flora.

Dawn Primarolo, minister for public health, said today: “We are trying to create a lifestyle revolution on a grand scale. There are very serious health consequences with allowing dangerous quantities of fat to build up in our bodies. This is not just an ad campaign – we are calling it a lifestyle revolution – it is a long-running concerted effort to change behavior.”

The television campaign launches on Saturday 3rd January with adverts designed by Aardman Animations, the people behind the much loved plasticine duo Wallace and Gromit. The engaging clip is designed to warn viewers of the health risks associated with being overweight and is targeted at helping young families change their lifestyle for good.

Change4Life is the biggest Government campaign ever launched and is expected to follow in the success of similar cross-media anti-smoking initiatives. Unlike anti-smoking public awareness strategies though, this campaign steers away from shock tactics and instead offers practical advice.

Critics have been quick to point out that the involvement of food companies in the campaign is a way for such corporations to cast their brand in a healthy light without actually changing the salt or fat content of their food. Tam Fry of the National Obesity Forum warned that junk food companies were donating millions to the campaign as a way of heading off the “regulation they fear”.

The Telegraph notes that “neither the leaflets nor the screen advertisements use the word obesity”, preferring instead to state that children could grow up to have “dangerous levels of fat in their body”. The campaign is designed to avoid pointing the finger at any one group, however, specifically avoiding talking about ‘fat bodies’ and blaming modern life rather than parents.

Let’s hope that the more kindly, blame-free approach of Change4Life gets the people of the UK off the sofa and helps to avert our obesity timebomb.

If you’re skeptical, the Big Question in The Independent casts a critical eye over the Change4Life campaign, asking whether the Government can really make us eat less.
On the other hand, it you want to get serious about improving your lifestyle there is stacks of information on how to eat better, move more and live longer on the Change4Life website.