Weight loss: how fast is too fast?

Has weight loss become a spectator sport? On last we could think of at least five series currently on TV dedicated to radical makeovers invariably including dramatic weight loss. It seems whenever we tune in we can follow staggering drops in weight all wrapped up into dizzying one hour packages. And while we all understand that it is the magic of TV that is able to deliver these turbo-charged makeovers (combined with a range of surgery, drastic diets, endless sessions with pricey personal trainers, not to mention the new designer wardrobe and hairdo) the underlying message is the same - you can have this now!

So here's the reality of it. More than 90% of all weight loss diets fail in the long term simply because they aim for rapid weight loss strategies that are unable to sustained in the long term. For the majority of the population weight loss should not exceed an average of 0.5-1kg each week. Anything more than this and you are generally losing vital muscle tissue and water. Remember also that for truly effective weight loss and body shaping you should also be increasing your physical activity (and therefore increasing your muscle mass).

Increased metabolism after exercise - does afterburn really exist?

Anyone who has embarked on a weight loss or get-fit program has undoubtedly heard about the benefits of 'afterburn' - the period of time directly after intense exercise where the body continues to burn calories at a higher than normal rate. Afterburn, or excess post-exercise oxygen consumption (EPOC), is caused during intense exercise. While exercising at higher intensities your muscles require more oxygen than is normally available so the body redirects oxygen from other areas. When you finish exercising areas of the body that are low in oxygen work to recover oxygen that they forfeited to the muscles. The body also needs to cool down and restore hormone balance, all of which requires oxygen.

However the impact of this 'afterburn', or excess post-exercise oxygen consumption (EPOC), is often exaggerated. Depending on the intensity of the workout EPOC can last from two to 15 hours and amounts to roughly 10 to 15 calories for every 100 calories burned during the actual exercise. Dr Cedric Byant, chief exercise physiologist for the American Council on Exercise describes it this way "If you go to the gym and burn 300 calories, your afterburn will be about 45 calories. That's one bite of a Snickers bar... People should not look at this as a licence to eat and drink all day thinking that their earlier workout is melting calories away". The important thing to remember is that the major contribution to weight loss is via the energy expended during the actual exercise - not the afterburn.

Source: Briley J, 2005, Afterburn dismissed, The Washington Post, reprinted in The Sydney Morning Herald; Health & Science Supplement, January 13 2005, p.3.

I didn't mean to say you're fat

While all of us can censor our thoughts, some of us are better at it than others, and it's easy to slip up. Stress, tiredness and being distracted increase the likeliness of "putting your foot in it", telling people what you really think of them, or making other social blunders. Researchers from the University of New South Wales investigated what happens when things go wrong. "The dinner party guest who puts his foot in his mouth could lack a crucial mental ability that stops the rest of us from blurting out our true feelings," says Associate Professor Bill von Hippel.

The UNSW researchers tested 71 people to monitor socially accepted behaviour under a range of tests and pressures. They first tested the participants' ability to hold their tongues and suppress irrelevant or inappropriate thoughts by sitting the Stroop test. The Stroop test requires participants to say the colour of the word, but not read the word itself. So, red should be read as "blue" not "red". The test monitors how effectively people can block out the irrelevance of the actual word and a widely used to judge inhibitory ability.

Participants were then divided into groups and asked to eat a chicken's foot under different levels of social pressure. The "high-pressure" group were served a chicken foot by a Chinese woman. The woman also described as the national dish of China and her personal favourite. The expectation being that most people attempted to be polite about the meal, despite personal misgiving. The "low-pressure" group were served a chicken foot by a woman who wasn't Chinese and said only that it was Chinese food.

Those who performed poorly on the earlier inhibitory Stroop test also performed poorly in this situation, acting in a way thought socially inappropriate, like pulling a face or saying "that's disgusting".

The experiment also manipulated attention by including distractions. The people in the study had to remember an eight-digit number while they were served the chicken foot. Their attention was now divided between remembering the number and conforming to social etiquette.

"Even people with good inhibitory ability were likely to behave inappropriately when distracted. This suggests that our ability to suppress our true feelings is disrupted under demanding conditions," von Hippel says. "It's well established that older people, very young people, and some brain-damaged people have less inhibitory control over thought and action. However this new research suggests that important variations occur in the general population in this inhibitory ability; some of us are naturally better at holding our tongue than others.

"Many people may be unable to inhibit the tendency to blurt things out even when they know the rules of social behaviour and want to behave appropriately...It's likely that people who can inhibit their true feelings in a challenging social situation are more likely to succeed in jobs requiring a high degree of social etiquette, such as international diplomacy".

"But even experienced career diplomats may find it increasingly difficult to act appropriately if they are distracted or fatigued, or as they grow older." The findings are soon to be published in Psychological Science.

Reference, Marshall J, 2005, 'Whoops, I didn't mean to say you're fat', ABS Science Online, 24th January 2005, http://www.abc.net.au/science/news/stories/s1287638.htm

Bigger women need more pre-pregnancy folate

Women with a body mass index greater (BMI) than 30 may need additional folate over and above current recommendation levels for women of childbearing age. Higher pre-pregnancy body mass index (BMI) is associated with increased risk of neural tube defects (NTDs) a condition linked with low maternal folate levels. Using data from the US National Health and Nutrition Examination Survey, it was estimated that women with a BMI greater than 30 would need to take an additional 350 microg/day of folate to achieve the same serum folate level as women with a BMI less than 20. To calculate BMI use the following equation:

Body Mass Index = weight (kg) / (height (m) x height (m)

Example 60kg, 154 cm woman = 60/(1.54 x 1.54) = 25.3 BMI

Source: Mojtabai R, 2004, Body mass index and serum folate in childbearing age women, Eur J Epidemiol, vol. 19, no.11, pp.1029-36.

Atkins and the new diet revolution

Health professionals have promoted a low fat, high carbohydrate diet for more than 20 years however the prevalence of overweight and obesity in Australia has continued to increase. However a low-fat, high carbohydrate diet does not guarantee health, especially if the diet contains high levels of simple sugars, low levels of complex carbohydrates and are nutrient poor.

In contrast to the low fat, high carbohydrate diet, a popular approach to weight loss is the high-protein, low-carbohydrate Atkins diet. The Atkins regimen promises quick weight loss without hunger, allows a wide range of foods and has simple “rules”. To read this editorial go to: http://www.mja.com.au/public/issues/181_10_151104/ril10624_fm.html

Regular dieters more likely to snack under stress

Women who report regularly dieting or restricting food intake are more likely to snack following a stressful incident or when required to complete intellectually challenging tasks than women who do not regularly diet. The British research to be published in this month's Journal of Eating Behaviour also concluded that regular dieters eat significantly more food under post-stress conditions than their non-dieting counterparts.

Lattimore P, Maxwell L, 2004, 'Cognitive load, stress, and disinhibited eating', Eat Behav, Nov; 5(4):315-24.

Dieting and exams don't mix

Australian research now shows that dieters are more forgetful when it comes to carrying out some complex cognitive tasks as it seems that some of their memory space is taken up thoughts of food, weight and body image. Researchers from Adelaide's Flinders University divided 92 female university students into three groups: those currently on a diet, those who had dieted in the past and those who had never dieted. The students then performed a series of cognitive tasks, such as tests recalling sequences of short and long words. The researchers found that those currently dieting struggled with complex verbal tasks. "You would think that dieting doesn't have much to do with verbal type things. But our study showed that when people were doing a task and then had to say something like numbers at the same time it affected their performance,".

Interestingly, only those who were currently dieting were affected; those who had once dieted performed on par with those who had never dieted. The researchers said this indicated it was the dieting behaviour itself that contributed to the poorer performance. The researchers reported that the study findings were consistent with the idea that it was dieters' preoccupying thoughts that led to poorer memory performance. Source: http://www.abc.net.au/science/news/health/HealthRepublish_1105852.htm

How does the Atkins diet work? The Atkins diet prescribes unlimited intake of fat and protein rich foods while virtually eliminating all carbohydrate foods. Even the amount of fruit is restricted. The world's most beautiful and famous people have taken Dr Atkins' advice and the book Atkins new diet revolution knocked Harry Potter off the best seller's list in the UK but how can a diet that encourages unrestricted intake of fat and protein rich foods without any regard for caloric intake actually work?

The truth is that until recently no one had yet systematically looked at how the Atkins diet actually worked. Not even Dr Atkins knew. During his lifetime Dr Atkins put forward a number of untested but possible theories to how you could eat more but still lose weight. He had speculated that turning fats and proteins into energy is a much more complicated chemical process than that of creating energy from carbohydrates and therefore the body would burn more energy breaking down a high protein, high fat diet. Dr Atkins also theorised that by eliminating carbohydrates your body would use up its glucose stores and then turn to fat for fuel. As your body burns fats it creates as a by-product molecules called ketones. Ketones are actually quite toxic so the body eliminates them in the urine and because ketones are in fact calories you could literally flush them down the toilet.

Researchers at Kansas University put Dr Atkins' theories to the test by comparing the heat, energy, ketone output of two identical twins. For two weeks one of the twins was put on the high fat, high protein Atkins diet. The other was put on a conventional low-fat diet. They were then locked in to a sealed chamber for a whole day and night where their levels of oxygen intake were measured in order to calculate how quickly their bodies were burning fuel. The twins' urine was also tested for ketone output. Results from oxygen measurements found that the twin on the Atkins diet did lose a few more calories (22), but barely enough to warrant the theory that you lose more calories when breaking down the high fat high protein Atkins diet. The results of urine tests were even more damning with the twin on Atkins losing less than a single calorie more than his twin on low-fat. So while these tests essentially disproved Dr Atkins' theories they did little to answer how in fact the diet did in fact work. Instead the answer may have come via a popular UK television series.

The TV series Diet Trials tracked the progress of four groups of dieters following four different diets. Three of the groups followed different variants of conventional low-fat low-calorie diets while the fourth group followed the Atkins diet. All dieters were required to keep a detailed diary of what they ate. All four diets performed similarly when it came to weight loss however it wasn't until researchers started to analyse the diet diaries from the Atkins dieters that something interesting emerged.

The diaries revealed that although those on the Atkins diet could eat as much as they liked they were actually eating as few calories as the low calorie dieters. So for all of the talk of limitless calories the Atkins dieters were eating less than they normally would (and therefore losing weight). At last it seems the mystery of the Atkins diet works may have been solved and it appears to have nothing to do with ketosis, burning more calories or limitless fat intake. Instead it seems that the Atkins diet works because protein makes you feel full and therefore curbs your appetite.

So what does this mean for Atkins dieters and the rest of us? Essentially it means that by increasing our protein intake we can curb our appetite (ever noticed for example how if you eat a salad sandwich it is not often that you would feel full, however if eating a similar sandwich with a protein source such as chicken, egg, cheese or tuna you feel full much earlier). Protein makes you feel full and actually tells your body to stop eating.

These findings also suggest that by increasing protein in the diet but ignoring Dr Atkins most dangerous recommendations (that is to reduce and eliminate fruits and vegetables and to eat more saturated fats) and still enjoy the appetite control and weight loss benefits without jeopardising your health. Source: www.abc.net.au/catalyst/stories/s1084112.htm.

Eat breakfast, lose weight - but don't order the bacon and eggs just yet. Breakfast eaters tend to have lower body mass index (BMI) than individuals who skip breakfast and obese individuals are more likely to skip breakfast. The number of overweight and obese American adults almost doubled between 1960 and 1994 from 12.8% to 22.5% while between 1965 and 1991, the proportion of American adults skipping breakfast increased from 14% to 25%. It has also been found that moderately obese women lose more weight when they consume 70% of their daily energy intake before noon instead of in the afternoon or evening. However American researchers investigating the relationship between breakfast type and BMI found that individuals reporting meat and/or egg as a common breakfast also had high BMIs. The best breakfasts for weight management, according to the study was cereal or toast. (References: Cho S et al. The effect of breakfast on total daily energy intake and body mass index: results from the Third National Nutrition Examination Survey. Journal of the American College of Nutrition. 2003; 22(4):296-302: Reproduced in Blackmores Online September 10, 2003).

US Scientists dub soft drinks as “cigarettes of obesity”

Low-fat, low-cal, low-carb. Atkins, South Beach, The Zone. Trendy diets may be distracting attention from something more insidiously piling on kilos: beverages. One of every five calories in the American diet is liquid. The nation's single biggest "food" is soda (soft drink). Now two groups of US researchers hope to add evidence to the theory that soda and other sugar-sweetened drinks don't just go hand-in-hand with obesity, but actually cause it.

Proving this would be a scientific leap that could help make the case for higher taxes on soda, restrictions on how and where it is sold - maybe even a surgeon general's warning on labels. "We've done it with cigarettes," said one scientist advocating this, Barry Popkin at the University of North Carolina in Chapel Hill.

However, those making the case against soda include some of the nation's top obesity researchers at prestigious institutions like Harvard and Yale.

"There are many different lines of evidence, just like smoking," said Dr David Ludwig, a Harvard paediatrician who wants a "fat tax" on fast food and drinks.

Beverage companies seem worried. Some are making sodas "healthier" by adding calcium and vitamins, and pushing fortified but sugary sports drinks in schools that ban soda. This could help them duck any regulations aimed at "empty calorie" drinks, said Jennifer Follett, a USDA nutritionist at the University of California in Davis.

"Even defining 'milk' is getting tough these days," with so many flavoured varieties and sweetened liquid yoghurts, she complained. "It tastes like you're sucking on ice cream."

Proving that something causes disease is not easy. It took decades with tobacco, asbestos and other substances now known to cause cancer, and met strong industry opposition. It would be especially tough for a disease as complex as obesity.

Diet is hard to study. Most people drink at least some sweetened beverages and also get calories from other drinks like milk and orange juice, diluting the strength of any observations about excess weight from soda alone.

Children are growing and gaining weight naturally, "so we have this added complication" of trying to determine how much extra gain is due to sweet-drink consumption, said Alison Field, a nutrition expert at Harvard-affiliated Children's Hospital in Boston.

Soft drink consumption rose more than 60 per cent among adults and more than doubled in kids from 1977-97. The prevalence of obesity roughly doubled in that time. Scientists say these parallel trends are one criterion for proving cause-and-effect.

Numerous studies link sugary drink consumption with weight gain or obesity. One by Ludwig of 548 Massachusetts schoolchildren found that for each additional sweet drink consumed per day, the odds of obesity increased 60 per cent.

Another at Harvard of 51,603 nurses compared two periods,
1991-95 and 1995-99, and found that women whose soda drinking increased had bigger rises in body-mass index than those who drank less or the same.

Biologically, the calories from sugar-sweetened beverages are fundamentally different in the body than those from food.

The main sweetener in soda - high-fructose corn syrup - can increase fats in the blood called triglycerides, which raises the risk of heart problems, diabetes and other health woes.

This sweetener also doesn't spur production of insulin to make the body "process" calories, nor does it spur leptin, a substance that tamps down appetite, as other carbohydrates do, explained Dr George Bray of the Pennington Biomedical Research Centre in Baton Rouge, Louisiana.

"There's a lack of fullness or satiety. The brain just seems to add it on," said Dr Louis Aronne, a Weill-Cornell Medical College doctor who is president of the Obesity Society.

Two studies by Penn State nutritionist Barbara Rolls illustrate this. One gave 14 men lemonade, diet lemonade, water or no drink and then allowed them to eat as much as they wanted at lunch. Food intake didn't vary, no matter what they drank.

The second study gave 44 women water, diet soda, regular soda, orange juice, milk or no drink before lunch. Total intake was 104 calories greater for those given caloric beverages than those given diet soda, water or no beverage. Caloric drinks didn't help women feel any fuller either.

Then there is the "jelly bean study." Purdue University researchers gave 15 men and women 450 calories a day of either soda or jelly beans for a month, then switched them for the next month and kept track of total consumption. Candy eaters ate less food to compensate for the extra calories. Soda drinkers did not.

Sugar-sweetened beverages affect the intake of other foods, such as lowering milk consumption. Popkin contends they also may be psychological triggers of poor eating habits and cravings for fast food.

He examined dietary patterns of 9,500 American adults in a federal study from 1999-2002. Those who drank healthier beverages - water, low-fat milk, unsweetened coffee or tea - were more likely to eat vegetables and less likely to eat fast food.

Conversely, "fast-food consumption was doubled if they were high soda consumers and vegetable consumption was halved," he said.

Harvard epidemiologist Eric Rimm saw a similar effect in a different federally funded study of more than 5,000 young adults. With high soda consumption, "you see this pattern of less healthy intake across the board," he said at the obesity meeting.

Many studies of different types link sugary drinks and weight gain or obesity. Some even show a "dose-response" relationship - as consumption rises, so does weight.

Collectively, they meet many criteria for proving cause and effect, Dr William Dietz, director of nutrition at the federal Centres for Disease Control and Prevention wrote in an editorial accompanying a study in February's Journal of Paediatrics.

Low-carb diets may increase cardiovascular risk

Reference: Nordmann AJ, 2006, Effects of Low-Carbohydrate vs Low-Fat Diets on Weight Loss and Cardiovascular Risk Factors: A Meta-analysis of Randomized Controlled Trials, Arch Intern Med. 2006 Feb 13;166(3):285-93.

French women are getting chubbier

Weight loss: how fast is too fast?

Increased metabolism after exercise - does afterburn really exist?

I didn't mean to say you're fat

Bigger women need more pre-pregnancy folate

Source: Mojtabai R, 2004, Body mass index and serum folate in childbearing age women, Eur J Epidemiol, vol. 19, no.11, pp.1029-36.

Atkins and the new diet revolution

Regular dieters more likely to snack under stress

Dieting and exams don't mix

US Scientists dub soft drinks as “cigarettes of obesity”

Low-carb diets may increase cardiovascular risk

Reference: Nordmann AJ, 2006, Effects of Low-Carbohydrate vs Low-Fat Diets on Weight Loss and Cardiovascular Risk Factors: A Meta-analysis of Randomized Controlled Trials, Arch Intern Med. 2006 Feb 13;166(3):285-93.

French women are getting chubbier

Weight loss: how fast is too fast?

Increased metabolism after exercise - does afterburn really exist?

I didn't mean to say you're fat

Bigger women need more pre-pregnancy folate

Source: Mojtabai R, 2004, Body mass index and serum folate in childbearing age women, Eur J Epidemiol, vol. 19, no.11, pp.1029-36. Atkins and the new diet revolution

Regular dieters more likely to snack under stress

Dieting and exams don't mix

US Scientists dub soft drinks as “cigarettes of obesity”

Source: Mojtabai R, 2004, Body mass index and serum folate in childbearing age women, Eur J Epidemiol, vol. 19, no.11, pp.1029-36.

Atkins and the new diet revolution