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Have we got the science of obesity back to front?

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Michelle D’urbano

IN PRINCIPLE, it sounds simple: eat less and move more. This dietary advice for tackling obesity has been around for decades. Yet, despite all the calorie counting, dieting and exercising, worldwide obesity rates just keep ticking up. People in the US, for example, were heavier in 2021 than they were in 2020, placing many more people at risk from diabetes and other serious chronic diseases. So why hasn’t this approach to weight control worked?

One possibility is that we haven’t tried hard enough. Perhaps we have lacked the discipline and willpower to maintain healthy dietary and exercise habits – a challenge made more difficult today for those surrounded by inexpensive, tasty, highly processed foods.

Or perhaps the problem is the focus on “calorie balance” itself. In a recent paper, my colleagues and I question the basic assumption of whether taking in more calories than you burn really is the primary cause of obesity. We argue that the evidence actually points the other way: we are driven to overeat because we are getting fatter (The American Journal of Clinical Nutrition, doi.org/gmtn3z).

This may seem incredible, but consider the adolescent growth spurt. As their growth rate speeds up, teenagers may eat hundreds of calories more each day than they used to. Does this “overeating” cause the rapid growth? Or does the rapid growth, which requires more calories to build new body tissues, make teens hungrier so they eat more? Clearly the latter, as adults won’t grow taller, no matter how much they eat.

The key to how this works in obesity is hormones, especially the fat-storage hormone insulin. Processed, rapidly digestible carbohydrates – foods like sweetened breakfast cereals, potato chips and sugary beverages – raise our insulin level too high. This causes our fat cells to take in and store too many calories, leaving fewer available for the rest of the body. A few hours after eating a high-carb meal, the number of calories in the bloodstream plummets, so we get hungrier sooner after eating.

Consider another example: oedema, in which excess fluid builds up in body tissues, such as the legs. People with oedema tend to become thirsty, despite the excess, because the fluid doesn’t stay in the blood where it is needed. From this perspective, the difficulty resisting hunger that so many dieters have isn’t a sign of poor discipline, but rather a biological problem involving how our bodies distribute the calories we consume.

The two opposing views of cause and effect in obesity have radically different implications for how to prevent and treat weight problems. Whereas the usual approach focuses on how much to eat, with prescriptions for daily calorie intake, in our view, the emphasis should be placed on what to eat.

Replacing processed carbs with high-fat foods – such as nuts, full-fat dairy, olive oil, avocado and dark chocolate – lowers insulin levels, making more calories from the meal available for the rest of the body. Counter-intuitively, higher-fat foods may help shed body fat, a possibility supported by clinical trials comparing high-fat diets with low-fat ones.

This way of thinking might help explain why calorie restriction usually fails long before a person with obesity approaches an ideal body weight. A low-calorie, low-fat diet further restricts an already limited supply of energy to the body, exacerbating hunger without addressing the underlying predisposition to store too many calories in body fat. Consequently, weight loss becomes a battle between mind and metabolism that most people will probably lose.

Although much more research will be needed to test this provocative idea, it is time to question the basic assumptions about cause and effect, calories and weight gain that have dominated our thinking for decades.

David S. Ludwig is a researcher at Boston Children’s Hospital @davidludwigmd

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Solar storms may cause up to 5500 heart-related deaths in a given year

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In an approximate 11-year cycle, the sun blasts out charged particles and magnetised plasma that can distort Earth’s magnetic field, which may disrupt our body clock and ultimately affect our heart



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17 June 2022

A solar storm

Jurik Peter/Shutterstock

Solar storms that disrupt Earth’s magnetic field may cause up to 5500 heart-related deaths in the US in a given year.

The sun goes through cycles of high and low activity that repeat approximately every 11 years. During periods of high activity, it blasts out charged particles and magnetised plasma that can distort Earth’s magnetic field.

These so-called solar storms can cause glitches in our power grids and bring down Earth-orbiting satellites. A handful of studies have also hinted that they increase the risk of …

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UK Covid infection rate rising, with more than a million cases in England | Coronavirus

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Coronavirus infections are rising in the UK, figures have revealed, with experts noting the increase is probably down to the more transmissible BA.4 and BA.5 Omicron variants.

The figures from the Office for National Statistics (ONS), based on swabs collected from randomly selected households, reveal that in the week ending 11 June an estimated one in 50 people in the community in England are thought to have had Covid – around 1.13 million people.

The figure is even higher, at one in 45, in both Wales and Northern Ireland, while it was highest in Scotland where, in the week ending 10 June, one in 30 people are thought to have been infected.

While the figures remain below the peak levels of infection seen earlier this year, when around one in 13 people in England had Covid, the findings are a rise on the previous week where one in 70 people in England were thought to be infected. Furthermore, the data reveals increases in all regions of England, except the north-east, and across all age groups.

Experts say that a key factor in the increase is probably the rise of the Covid variants of concern BA.4 and BA.5.

“Infections have increased across all four UK nations, driven by rising numbers of people infected with the BA.4 and BA.5 Omicron variants,” said Kara Steel, senior statistician for the Covid-19 Infection Survey.

While Steel said it remained too early to say if this was the start of another wave, others have warned it may already have begun, with increased mixing and travelling among other factors fuelling a rise in cases.

Among concerns scientists have raised are that BA.4, BA.5 and another variant on the rise, BA.2.12.1, replicate more efficiently in human lung cells than BA.2.

Prof Azra Ghani, an epidemiologist at Imperial College London, said the latest figures were not surprising, and might rise further.

“This increase in infection prevalence is likely due to the growth of the BA.4 and BA.5 Omicron subvariants, which as we have seen elsewhere in Europe, appear to be able to escape immunity generated from previous Omicron subvariants,” she said.

“It is therefore possible that we will continue to see some growth in infection prevalence in the coming weeks and consequently an increase in hospitalisations, although these subvariants do not currently appear to result in any significantly changed severity profile. This does however serve as a reminder that the Covid-19 pandemic is not over.”

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NHS to offer women in England drug that cuts recurrence of breast cancer | Breast cancer

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Thousands of women in England with breast cancer are to benefit from a new pill on the NHS which reduces the risk of the disease coming back.

The National Institute for Health and Care Excellence (Nice) has given the green light to abemaciclib, which cuts the chance of breast cancer returning after a patient has had surgery to remove a tumour.

Trials showed that patients who had the drug with hormone therapy had a more than 30% improved chance of their cancer not coming back after surgery, compared with hormone therapy alone.

“It’s fantastic thousands of women with this type of primary breast cancer will now have an additional treatment option available on the NHS to help further reduce the risk of the disease coming back,” said Delyth Morgan, the chief executive of charity Breast Cancer Now.

“The fear of breast cancer returning or spreading to other parts of their body and becoming incurable can cause considerable anxiety for so many women and their loved ones.

“New effective treatments such as abemaciclib, which can offer more women the chance to further reduce the risk of the disease recurring, are therefore extremely welcome and this is an important step change in the drug options available for this group of patients.”

The twice-a-day pill is suitable for women with hormone receptor-positive, HER2-negative, node-positive early breast cancer at high risk of recurrence who have had surgery. About 4,000 women will benefit initially, Nice said.

Helen Knight, the interim director of medicines evaluation at Nice, said the draft recommendation came less than a month after abemaciclib received its licence.

“The fact that we have been able to produce draft recommendations so quickly is testament to the success of our ambition to support patient access to clinically and cost effective treatments as early as possible,” said Knight. “Until now there have been no targeted treatments for people with this type of breast cancer.

“Abemaciclib with hormone therapy represents a significant improvement in how it is treated because being able to have a targeted treatment earlier after surgery will increase the chance of curing the disease and reduce the likelihood of developing incurable advanced disease.”

Abemaciclib works by targeting and inhibiting proteins in cancer cells which allow the cancer to divide and grow. It normally costs £2,950 for a packet of 56 150mg-tablets, but the manufacturer, Eli Lilly, has agreed an undisclosed discounted price for NHS England.

“Thanks in part to this latest deal struck by NHS England, NHS patients will be able to access another new targeted drug for a common and aggressive form of breast cancer,” said Prof Peter Johnson, the cancer director of NHS England.

“Abemaciclib, when used alongside a hormone therapy, offers a new, doubly targeted, treatment option, helping to increase the chances of beating the cancer for good, as well as meeting the NHS’s commitment to delivering improved cancer care under our long-term plan.”

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