An Israeli study showed how MRI imaging can be used to map excess fat in the body As part of the largest human fat mapping project in the world, Israeli researchers are helping to define medical protocols for specific treatment of the various fat stores in the human body
An extraordinary Israeli study that continued over a particularly long period of time among hundreds of subjects (a CENTRAL study), published in the world's most prestigious journal in the field of liver research -Journal of Hepatology, used for the first time, the MRI imaging device in order to map the accumulation of excess fat in different areas of the human body and to check over time whether different diets have a different effect on those excess fat stores in different organs of the body.
The researchers found that a reduced-carbohydrate Mediterranean diet had a more pronounced effect on the retreat of fat in the liver, around the heart, and in the pancreas compared to a low-fat diet of equal calories - although the weight loss was similar. It was also found that moderate physical activity reduced intra-abdominal (visceral) fat deposits.
The different fat stores in the human body reacted differently to the intervention: together with a moderate weight loss, the liver fat was reduced by 30%, the fat around the heart by 11% (volume reduction of about 70 ml), the intra-abdominal fat was reduced by 25%, while the fat stores in the pancreas and in the muscle decreased by only 1-2%.
The researchers reported that the dramatic reduction (30%) that was observed in the percentage of fat in the liver while losing moderate weight, is in the long term the main factor in reducing the health risk arising from obesity. The researchers also proved that this is a better predictor than the reduction in intra-abdominal fat, which until now was considered the main predictor. The finding contributes to the emerging understanding that in many people suffering from obesity, excess accumulation of fat in the liver is not only a marker, but may be a risk factor for morbidity resulting from obesity such as: cardiovascular diseases, and diabetes.
The group of researchers from Ben-Gurion University of the Negev, Leipzig University in Germany, and Harvard, led by Prof. Iris Shai from Ben-Gurion University, in collaboration with Soroka Hospital and the Dimona Nuclear Research Center, examined the significance of the reduction in liver fat (compared to intra-abdominal fat), when approx. 300 people with overweight and/or a disorder in the lipid metabolism were instructed to consume one of two reduced calorie diets: a Mediterranean diet, and a low-fat diet. Close monitoring of the participants for 18 months showed that they did change their dietary habits according to the nutritional intervention group to which they were drawn. In addition, in collaboration with the doctoral student, now Dr. Yiftah Gefner, a young researcher at Tel Aviv University, Prof. Ilan Shalf and Dr. Dan Schwarzfox from Soroka University Hospital and Prof. Assaf Rodich from Ben-Gurion University, each participant underwent a magnetic resonance imaging (MRI) ) included a bodysuit to assess the distribution of fat in the body before, during and at the end of the intervention period.
The CENTRAL study is considered a breakthrough in the way of finding unique protocols for nutritional treatment of specific and different fat stores in the human body while using the most accurate MRI technology today to map and quantify the fat stores in the various organs of the human body and understand their meaning and function.
The "Central" study, which is unprecedented in its scope and length, contributed a vast information library of thousands of intracorporeal imaging layers to locate and map fat stores in the human body (it turns out that there is, during life, a leakage of fat cells to various organs and the role of fat there ranges from a protective factor, from neutral to toxic), and monitoring the changes in their scope and volume over time. The Israeli researchers who developed specific fat quantification technologies paved the way for a deeper and more accurate understanding of the dynamics of weight loss during a diet.
Background: the obesity epidemic
As a group, people who suffer from obesity are exposed to higher rates of morbidity than thin people, especially cardiovascular diseases and type 2 diabetes. However, with the increase in the prevalence of obesity in the world, which is now the property of approximately 24% of the adult population in Israel (and over 40% in the USA), it becomes clear that this excess risk that accompanies obesity characterizes subgroups of loci in obesity more than other subgroups. Therefore, one of the significant challenges today is in identifying the subgroups, or "types" of obesity in the population, and finding different interventions with the aim of improving their health in a more appropriate way. For example, it turned out that when the accumulated adipose tissue is more inside the abdominal cavity, the "cardio-metabolic" risk is higher than with the accumulation of excess adipose tissue under the skin.
This understanding, along with various characteristics of the intra-abdominal fat, also led to the thought that the intra-abdominal fat is a major morbidity factor in obesity, and that the effectiveness of various interventions should also be tested based on their unique ability to reduce the accumulation of intra-abdominal fat. At the same time as the accumulation of intra-abdominal fat, the percentage of fat in the liver also increases in most people with obesity. The significance of this accumulation is still controversial (the chicken and the egg dilemma: there is still no consensus as to whether "fatty liver disease" is a disease in itself, and many experts who think that without additional changes in the liver, such as the development of inflammation and/or fibrosis (deposition of proteins outside the cells), it has no meaning very healthy). Indeed, there are currently no specific drugs for the treatment of fatty liver, but a general recommendation to lose weight.
Against this background, a group of researchers from Ben-Gurion University, Leipzig University in Germany, and Harvard, led by Prof. Iris Shai from Ben-Gurion University of the Negev, in collaboration with Soroka Hospital and the Kariya for Nuclear Research Dimona, examined the significance of the reduction in liver fat (compared to intra-abdominal fat), When about 300 people with excess weight and/or a disorder in the lipid metabolism were instructed to consume one of two reduced-calorie diets: a Mediterranean diet, and a low-fat diet. Close follow-up of the participants for 18 months showed that they did change their dietary habits according to the nutritional intervention group to which they were drawn. In addition, with the cooperation of the doctoral student, now Dr. Yeftah Gefner, a young researcher at Tel Aviv University, Prof. Ilan Shalf and Dr. Dan Schwarzfox from Soroka University Hospital and Prof. Assaf Rodich from Ben Gurion University, each participant underwent a magnetic resonance imaging (MRI) scan. A bodysuit to assess the distribution of fat in the body before, during and at the end of the intervention period.
Despite a similar weight loss of the subjects, advantages were found for the Mediterranean diet over the low-fat diet in a number of indices used to assess cardiac risk and the development of diabetes. In 3 different risk indices for assessing the risk of suffering from heart disease in the next 10 years, indices that weigh different parameters, such as the subject's age and gender, blood fat and sugar levels, and blood pressure, a more significant decrease in the risk of heart disease was found in participants who adopted a Mediterranean diet. The difference between the two intervention arms remained statistically significant even when the degree of weight loss of the subjects was standardized, so the reduction of cardiac risk is an effect of a healthy diet beyond the extent of the diet's ability to cause weight loss. However, the most innovative finding in the study was observed when the researchers examined the dependence of the advantage of the Mediterranean diet over the competing diet on the degree of reduction of intra-abdominal fat or liver fat: while adjustment for the reduction of intra-abdominal fat did not eliminate the statistically significant difference between the diets, adjustment for the degree of reduction (higher) in liver fat masked this difference. This finding supports the possibility that the reduction in liver fat does not only reflect, but mediates, the relationship between the dietary intervention and the reduction in the risk of future development of heart disease.
According to Prof. Shay: "A healthy diet, while losing moderate but consistent weight, has a much more dramatic effect than we thought on the morbid fat deposits associated with diabetes and cardiovascular diseases. This research may contribute to the accuracy of medical protocols in the future that will be more specific to the type of fat that requires treatment and the preferred strategy for it." Prof. Shelf, director of the imaging department at Soroka, emphasizes that "the study joins other recent studies that demonstrate the accuracy of quantitative magnetic resonance technology in measuring the amount of liver fat. At the same time, the development of similar and other technologies that could in the future be a substitute for the need to take liver biopsies from patients, and will allow repeated measurements for a more personal assessment of the health risk of a patient suffering from obesity, and of his response to treatment."
These days this research group is finishing another innovative clinical trial - (Direct Plus) in which the question of whether the green Mediterranean diet (a proposal for an improved version of the Mediterranean diet rich in polyphenols derived from green plant components) has an advantage in affecting liver fat and other body systems such as the brain, the genome, The microbiome, the heart and the other fat stores. This clinical trial joins an impressive line of clinical nutrition trials by the Israeli research group under the leadership of Prof. Iris Shay, characterized by unprecedented orders of magnitude in scope, length and innovative technological uses to examine basic nutritional questions using the methods of drug trials within extensive international cooperation. These experiments have already succeeded in contributing with their innovation to breaking conventions and changing medical protocols in the world.
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