With obesity a worldwide epidemic, we spoke to Dr Stacey Lockyer, Nutrition Scientist, British Nutrition Foundation, about how these global findings impact nutrition trends and calorie consumption in the UK.
Calories and Cells: What's the link?
São Paulo Research Foundation (FAPESP), a leading regional grant-funding body in Brazil, carried out experiments on animals, concluding that caloric restriction results in cell-based changes that can have a preventative effect on the onset of some diseases.
Presenting their findings at FAPESP Week London in February 2019, the studies were carried out by the Center for Research on Redox Processes in Biomedicine, a Research, Innovation and Dissemination Centers (RIDCs) funded by São Paulo Research Foundation (FAPESP).
Sharing insights on how calorie intake directly influences the performance of a variety of cells, Alicia Kowaltowski, a professor at the USP Chemistry Institute (IQ-USP), commented: “We are looking at how changes to the diet affect metabolism and how that ends up changing the odds of having diseases associated with ageing.”
Calorie restriction and disease prevention
Through experimenting on mice in one of the group’s studies, the researchers analysed the effect that a low-calorie diet can have on protecting the brain from neuronal cell death. This loss of cell performance is associated with various diseases including Alzheimer's, Parkinson's, epilepsy and cerebral vascular accident (CVA).
After splitting the mice into two groups, the researchers monitored the average number of calories the group with no caloric restrictions would eat, before then feeding the other group 40% fewer calories. Following a period of 14 weeks, mice in both groups were given an injection that contained a particular substance known to cause seizures, damage and neuronal cell death.
The experiment found that the animals in the group that had no dietary restrictions did have seizures, while those with a restricted calorie intake did not. In vitro tests were then carried out to calculate the effect when the organelles of the brains of the mice were isolated.
Mitochondria are the specific organelles that generate energy in cells. When researchers introduced calcium, the uptake was higher in the mitochondria of the calorie restricted group where the mineral’s level was noted as pathologically high.
Insulin production
After engaging in experiments using beta cell cultures that stay in the pancreatic islets and produce insulin, the researchers concluded that the pancreas, restricting calories could improve cell response to raised levels of blood glucose.
The researchers looked at the blood serum of mice that had experienced a range of diets to ascertain the impact of calorie restriction. They found that in the cells of the animals that ate fewer calories, insulin secretion through the beta cells was typical: it was low when the glucose was low and correspondingly high when the glucose was high.
However, this was not the case in the animals eating more calories and who, subsequently, became obese. As a result of this experiment, the University of Sao Paulo researchers have raised the suggestion of whether there may be a circulating blood factor that acutely modifies beta cell function.
When it comes to healthy ageing, Kowaltowski emphasised that importance of understanding how metabolism works is for the prevention and cure of metabolic diseases and prognostic factors of unhealthy ageing like obesity.
"Obese individuals are much more likely to have age-related diseases. This includes neurodegenerative diseases like Alzheimer's, proliferative diseases like cancer, and metabolic diseases themselves, such as Type 2 diabetes, hyperlipidemia, heart attack and CVA. Obese people have a higher incidence of all of these," highlighted the researcher.
“Public Health England has estimated that on average, adults consume approximately 195 excess calories per day, and overweight and obese adults consume approximately 320 excess calories per day,” Dr Stacey Lockyer, Nutrition Scientist, British Nutrition Foundation, confirmed.
As such “two-thirds of adults in the UK are overweight or obese which increases the risk of developing chronic diseases such as heart disease, type 2 diabetes and cancer,” Lockyer went on to share.
Calories and Cells: What needs to be done?
Stating that the prevention of obesity can lead to the prevention of disease, Kowaltowski went on to say: “That's why if we try to understand the mechanisms through which obesity increases those diseases, we will have more tools to fight and prevent them.”
Examples of low-density foods:
- Fruit
- Vegetables
- Wholewheat pasta
- Brown rice
- Pulses
- Non-creamy soups and stews
- Reduced fat dairy foods
- Lean protein sources such as trimmed meat, white fish, seafood and eggs
As research to support and demonstrate the link between calories intake and the onset of preventable diseases strengthens, organisations and charities such as the Brtish Nutrition Foundation are looking for strategies to combat obesity.
“Adopting evidence-based weight loss strategies that are healthy and balanced is key. It is clear that there is no ‘one size fits all’ approach to weight loss - different weight loss strategies work better for different people due to their lifestyle and preferences,” Lockyer highlighted.
Commenting on what some evidence from human studies reveals, Lockyer suggested that “reducing the energy density of your diet can aid weight loss”.
Day-to-day, this means eating foods with fewer calories per gram, otherwise known as low energy density foods including foods with high fibre and/or water content.
Equally, consumers can be mindful of reducing calorie intake by limiting the consumption of high energy density foods such as fried foods, fatty meat, chocolate, crisps, cakes, biscuits, pastries and sugary drinks.
“Though importantly, a small number of high energy density foods (oily fish, nuts and unsaturated oils and spreads) form part of a healthy, balanced diet,” Lockyer stressed.
“Choosing low energy density foods means that a greater quantity of food can be consumed for fewer calories, reducing hunger and there is also some evidence that protein and fibre can keep us fuller for longer,” Lockyer concluded.
