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It is known that different types of diets can affect the accumulation of fat in the peripheral areas of the body and result in the development of metabolic syndrome. Researchers hypothesized that consuming food from energy sources, mainly from fat or carbohydrates in diets containing the same types of foods, would differentially affect the ability to reverse metabolic syndrome and peripheral fat accumulation.
A clinical study was then developed where 46 men between the ages of 30 to 50 years and with a body mass index (BMI) of more that 29 and waist circumference of more than 98 cm, were randomly selected to consume a very high fat and low carbohydrate (VHFLC - where 73% of the energy consisted of fat and 10% of carbohydrates) or a low fat and high carbohydrate (LFHC - where 30% of the energy consisted of fat and 53% of carbohydrate) diet for 12 weeks.
These diets were equal in energy, consisting of 8750 kilojoules (kJ) per day, and consisted of 17% protein, a similar food profile and lower-glycaemic, low-processed foods (including high amounts of vegetables and rice as an alternative to flour-based products, with fat sources being mainly cold-pressed oils, cream and butter). Therefore, the food in both diets were similar but just varied slightly in quantity.
The intake of total and saturated fat and carbohydrates in the VHFLC and LFHC groups reported the following findings:
- In both diets there was a reduction in peripheral fat mass of between 1350 and 1650 cm3, central subcutaneous abdominal fat mass of between 1650 to 1850 cm3, waist circumference of 11 to 13 cm and total body weight of 11 to 12 kg. This occurred despite the VHFLC diet consisting of more food.
- The cholesterol and triglyceride levels of both groups had reduced, but showed different responses in high-density lipoprotein (HDL - "good") cholesterol where it increased in the VHFLC group and in total and low-density lipoprotein (LDL - "bad") cholesterol where they were decreased in the LFHC group.
- There were similar reductions in both groups regarding glycated haemoglobin, insulin C-peptide and insulin levels.
- There were very important improvements in metabolic markers in the blood stream in the VHFLC group which were observed after 8 weeks, and there were acute and gradual improvements in the LFHC group.
The clinical significance
The intake of saturated fat in the diet has been long thought to be the cause of cardiovascular diseases by elevating LDL ("bad") cholesterol levels in the blood. The researchers of the study proved that there was no significant increase in LDL cholesterol by consuming a higher fat content. Instead, what was discovered was that HDL (“good”) cholesterol levels increased on the VHFLC diet.
The researchers did point out though that future studies would be needed to examine which individuals would have to limit their intake of saturated fats.