It's true: hungry shoppers buy more food

A scientific study has finally given credence to what many people intuitively know: never go shopping on an empty stomach.

Fasting or food deprivation in a restrictive diet is well-known to increase both the quantity and quality of food a person eats when they break their fast or diet. It seems logically then that this would explain why advice is given to people trying to eat less to avoid shopping when hungry. Surprisingly though, the area of hunger and shoppers’ purchases hasn’t been well studied.

Do people really buy more when they are hungry and are they more likely to choose high-kilojoule foods compared to someone shopping on a full stomach? Researchers from Cornell University set out to study this serious gap in the dieting folklore mythology to see if there may be a kernel of truth to it.

Sixty eight adults took part in the study which was designed in the first part to be a lab experiment. Each person was asked to not eat for 5 hours before the late afternoon experiment kicked off. Just before the participants were let loose on the online simulated grocery store, half of the people were given some wheat biscuits to curb their well-developed hunger. The online store offered a variety of consumer staples as well as plenty of salty and sugary energy dense snacks.

People who hadn’t eaten any food in the afternoon were more likely to choose high-kilojoule foods when they were set loose in the simulated supermarket. Compare that against people who were given a snack before shopping: they bought less of the energy dense foods.

Interestingly, both groups of people bought an equal amount of the low-kilojoule food staples. So the hungry shoppers not only bought more food, but specifically more of the snack types.

Rather than just using a simulated supermarket, the researchers also looked at patterns in shopping purchases in real supermarkets. Shoppers were more likely to buy a greater amount of energy dense foods in the hours leading up to dinnertime of 4 to 7 pm compared to earlier in the day in the hours of 1 to 4 pm.

Details of the study can be found in JAMA Internal Medicine

What is all means
Hungry shoppers are more susceptible to buying energy dense foods which is not helped by the way supermarkets are cleverly designed to make us buy more at every turn. One way to fight back against this is to either shop soon after meals, or enter the supermarket after chowing down on a healthy snack.

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Pay attention if you want to lose weight

Attentive eating is a hot topic in nutrition research. A recent review of the research to date finds that mindful eating can be a powerful behaviour change in helping with weight loss.

Diets come and go, yet few offer any real long-term solution for weight loss and weight maintenance. An overall change in lifestyle and behaviour is fundamental to addressing decades of slow weight gain and failed dieting.

One very simple strategy to help with weight loss, so simple that it puts to shame many complex dietary recommendations, is to be more mindful when it comes to eating. Mindfullness can be described as learning to pay attention to the present moment experience and to let thoughts and feelings come and go without providing judgement.

Applying the principle of mindfullness to eating can be as simple as focussing on what is currently being eating. Removing distractions such as television watching at meal times, savouring the taste of food as it is eaten slowly, and even a simple recall of what has been eaten recently all appear effective in changing future decisions about what and how much to eat.

Just how effective attentive eating can be has been the subject of a recent review published in the American Journal of Clinical Nutrition. From 24 studies examined, the findings were clearly in favour of attentive eating being able to change food consumption habits. Eating when distracted was seen to increase food intake not only at the meal time, but several meals after the distracted eating episode as well. In contrast, having a better memory of what was recently eaten reduces how much is eaten.

What is all means
Mindful eating free of mindless distractions combined with mindful recall of food previously eaten is an important part of any weight loss behaviour change targeted at eating less.

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Can lack of sleep make you fat?

Yet another clinical study has confirmed the growing body of evidence linking inadequate sleep to obesity.

One of the more surprising factors linked to weight gain is lack of sleep. More and more research studies are finding that poor sleep patterns and insufficient sleep are closely linked to weight gain and obesity.

The mechanism linking poor sleep to weight gain is not entirely understood, but is likely related to how signals from the brain which control appetite are altered by sleep restriction. Inadequate sleep can alter the levels of the appetite-stimulating hormone ghrelin while reducing production of the fullness-feeling hormone leptin. This can lead to increased food consumption without a similar increase in energy expenditure.

Much of the sleep research though has involved either observational studies looking at habitual sleep patterns and body weight, or single-night studies done in a controlled sleep laboratory. Now researchers have extended the research to look at how 5 nights of poor sleep can affect energy expenditure and hormone levels with the results published in the journal PNAS.

Sixteen healthy adults took part in the study. Their average normal night’s slumber was just over 8 hours and all were at a healthy body weight with no heavy users of alcohol or caffeine and none were taking medications.

The sleep deprivation conditions involved making participants wait 2 hours past their normal bedtime before being allowed to sleep and rousing them from their slumber 2 hours earlier than normal. This was repeated for 5 days in a row under controlled laboratory conditions where energy expenditure, diet and blood tests were carefully monitored.

The poor sleep patterns did result in a small increase in energy expenditure of around 5% which at first blush seems positive. Yet this was more than offset by a higher amount of food eaten, especially after dinner at night time, which caused an average weight gain of 0.82 kg over just 5 days.

What surprised the researchers was that changes in hormone levels were in favour of blunting food intake, yet despite this, overeating still occurred. One theory to explain this is that it was the change in the circadian rhythm resulting in more hours of wakefulness that altered the normal eating pattern.

Showing that weight gain is not set in stone, when the participants reverted back to a normal sleep pattern, they ate less food and a small amount of weight loss seen.

A nice article here explores the top 10 myths about sleeping - clinging to bad habits and buying into sleep myths can keep you perpetually tired

What is all means
Sleep plays an important part in energy metabolism. Disruption of a healthy sleep cycle can throw the body out of kilter, resulting in more food eaten and more weight gained. For someone that is struggling to control their weight, it may pay to look more closely at how they prioritise quality sleep in their life.

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Creatine loading: not just for athletes

Use of the popular sports supplement creatine has shown promise in a small-scale clinical trial in helping people with diabetes get their blood sugar under control.

Creatine is a popular nutritional supplement widely used across many sports. Creatine occurs naturally in the body, and is found mostly in muscle tissue. Creatine is a normal part of the foods we eat, but meat, fish, and poultry are the only foods with any appreciable amounts.

The main role of creatine is to provide a limited, but rapidly accessible fuel to replenish ATP stores (ATP is the main form of ‘energy currency’ in the muscle cell). Creatine is thought to act as a buffer to save ATP supplies for when they are needed the most. Creatine supplementation has been shown to enhance exercise performance in sports involving repeated sprints or bouts of high intensity exercise, separated by short recovery intervals.

Creatine in diabetes

One very novel direction of research to do with creatine supplementation is how it may benefit people with impaired glucose tolerance such as that seen in type 2 diabetes. Creatine supplementation together with muscle contraction from exercise can stimulate the mechanisms that muscle cells use to take up glucose. This could offer a therapeutic benefit in improving glucose control in people with diabetes.

Just published in the journal Medicine & Science in Sport & Exercise, a 12-week study involving 25 people with pre-existing type 2 diabetes, a body mass index above 30 kg/m2 (classified as obese) and who were otherwise inactive took part in a clinical trial.

Each person was enrolled in a regular exercise program for the 12 weeks and was randomly allocated to receive either creatine (5 grams per day) or a placebo. Both the participants and the researchers were blinded to the treatment each person was allocated to.

At the end of trial, there were marked reductions in measures of glucose control in the group taking the creatine which was not evident in the placebo group. The creatine group also showed more movement to the cell surface membrane of the critical transporter of glucose (GLUT4). This last finding is important as one of major consequences of insulin resistance as seen in type 2 diabetes, is an inability of insulin to cause GLUT4 to move to the cell membrane so it can remove glucose from the blood.

The main measure of glucose control was glycosylated haemoglobin (HbA1C) which is represents the average glucose levels in the blood over several months. In the creatine group, it dropped from 7.4% to 6.4% and was relatively unchanged in the control group from 7.5% to 7.6% at the end of 12 weeks.

Don’t be misled by the apparent small change in glycosylated haemoglobin for the creatine group. This magnitude of reduction in HbA1C is very clinically important and has the potential if maintained to mean a reduction in whole host of short- and long-term complications from the disease.

What it all means

Results from this very small pilot study show some very promising findings. Confirmation by larger studies and closer scrutiny of any potential health risks (though creatine supplements are considered very safe to use) could start to move this supplement out of the gyms and sports fields, and into the medical world.

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Beating cancer one step at a time

Cancer is a big killer of Australians, yet a person has much in their own control in preventing many of these cases of cancer. Being physically activity is one of them and is now recognised as a potent ‘cancer-preventing’ habit.

Regular physical activity can reap big rewards in cutting a person's risk of cancer with estimates of a 20 to 40% lower risk of colon and post-menopausal breast cancer and a potential benefit in lowering prostate cancer risk too. Being active also comes with the added bonus of improving fitness, keeping bones healthy, keeping body weight in check and reducing stress. Wins all around.

So how much physical activity is enough? All physical activity is beneficial, but for cancer prevention the scientific evidence suggests up to one hour of moderate activity or 30 minutes of vigorous activity each day is likely the best. Moderate activity is anything that causes a slight, but noticeable rise in breathing or heart rate such as brisk walking, medium-paced swimming or recreational cycling. Examples of vigorous activity include running, aerobics, squash, fast cycling and football.

A fascinating field of research is now looking at the role that physical activity can play in people already diagnosed with cancer. Several research studies are now linking regular physical activity after a cancer diagnosis with lower rates of cancer-related mortality, particularly from breast and colorectal cancer.

One study published in the Journal of Clinical Oncology in 2006 found that women who had been diagnosed with colorectal cancer and undertook the equivalent of a brisk walk for one hour per day had a 61 percent lower risk of dying from their cancer compared to inactive persons. Importantly, how active the women were before diagnosis of cancer had no effect on their chance of dying after diagnosis which shows that getting more active after a cancer diagnosis is likely beneficial.

Another research study from the same journal, involving people with advanced colorectal cancer, found that those undertaking the equivalent of a brisk walk for one hour per day had half the risk of a cancer relapse compared to inactive people. 

The results from the two studies in people with colorectal cancer support previous published work showing a reduction in risk of cancer recurrence with increased levels of physical activity in women with breast cancer. 

What this all means is that physical activity after a cancer diagnosis may offer some benefits in improving survival from the disease. Because physical activity has few downsides, it is something that all cancer survivors should aim to include more of in their lives. For a person with cancer, undertaking a new ‘fitness regime’ is something that should be undertaken after appropriate advice from a health professional.

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Is it time to shine for vitamin D?

Vitamin D is attracting more than its fair share of attention in both the scientific and public spotlight. Long known for its role in keeping bones healthy, there is a growing list of health benefits being linked to this so called 'sunshine vitamin'. The list of disease candidates is long and includes diabetes, cardiovascular disease, multiple sclerosis, obesity, autoimmune diseases, cancer, respiratory diseases, and even some mental health conditions such as schizophrenia. The field of research is fast-moving so it is hard to determine where the truth may lie.

Unlike most other nutrients that we obtain from food, vitamin D is one where only a few foods contain it. Fortunately, we can make all we need from sun exposure, which makes up more than 80 percent of the vitamin D in our body.

Vitamin D deficiency is now considered a major public health issue in Australia and New Zealand. Groups such as the housebound, community-dwelling older people, disabled people, those in residential care, dark-skinned people (particularly those modestly dressed), and people who regularly avoid sun exposure or work indoors are all at risk of developing deficiency. Infants born to deficient mothers are also a serious concern.

Bone and muscle health
The most clearly established role of vitamin D is to keep calcium and phosphate levels in balance, and with that comes healthy bones and good muscle function. Severe vitamin D deficiency causes impaired bone mineralisation, resulting in rickets in children and osteomalacia in adults. Osteomalacia results in bone and muscle pains, and an increased risk of fractures.

It is not just healthy bones that vitamin D helps with. Muscle has specific receptors for vitamin D which promote muscle protein synthesis and muscle growth. Vitamin D deficiency can affect a person's balance which if combined with poor muscle strength, puts a person at greater risk of falling and potentially a life-threatening bone fracture.

Cancer
A role for vitamin D as a potential agent in the prevention of cancer is an emerging area of research. A higher risk of developing and dying from three of the most common cancers seen in western countries (breast, prostate and colon cancer) has been linked with living at higher latitudes, likely because of the result of reduced exposure to sunlight. Observational studies of large groups of people followed over time also point to a link between low levels of vitamin D and cancer. Although observational studies cannot prove a cause-and-effect relationship, the weight of evidence is growing and is pointing in the right direction. 

Influenza
The seasonal nature of influenza outbreaks is one that is not entirely understood by medical researchers. One interesting theory is that vitamin D could explain the connection, because influenza is more common in the winter during times of less sunlight.

Studies looking at vitamin D supplementation and the prevention of osteoporosis gave an interesting finding that people taking vitamin D supplements were three-times less likely to report cold and flu symptoms. Other studies have seen a correlation between low vitamin D levels and higher influenza risk. Providing higher quality evidence, a purpose-designed clinical trial found that children given a daily vitamin D supplement during winter were 42% less likely to become infected with seasonal flu compared to those who were given a placebo.

If the findings from the recent influenza research were confirmed in larger trials, it opens the door to an effective way to boost the immune system of people going into the flu season, especially those at greatest risk of being infected. 

Other roles
Interest in vitamin D also extends to cardiovascular where rates of disease are higher in countries at higher latitudes, and during winter months where sunlight exposure is less. Vitamin D is also an important part of the body’s immune system, with low levels linked to autoimmune diseases including type 1 diabetes and multiple sclerosis.

Despite strong correlations between vitamin D and a range of diseases, the latest research represents only a thumbnail sketch of the bigger picture. As scientists build upon this research, it potentially could mean a future where the sun is seen more as a friend than a foe – at least in small doses. 

What is all means
Vitamin D's role in human health is diverse, ranging from its important role in bone health to more speculative roles such as cancer prevention. The promising findings from new areas of vitamin D research need to be tempered with the quality of research studies behind them until more definitive clinical trials are undertaken.

Considering that we rely on UV radiation, a known carcinogen, to synthesise the majority of our vitamin D, this creates a major public health dilemma of how to balance health benefits against disease risk. Adopting a food fortification policy, as seen in some countries, or wide-spread supplementation in at-risk groups may be the most practical measure to alleviate suboptimal vitamin D levels in many people today.

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