An epidemic of obesity

            Most of us regulate our body weight tightly. Even so, the growing number of people becoming obese indicates that our sedentary lifestyle and high-fat diet are taking their toll (негативно отражаться). The need for scientists to develop a greater understanding of how the body balances energy input with its energy requirements is going to be of great importance in averting major health problems.

            Lipids. Lipids are a varied group of biochemical compounds, but they are grouped together because of their non-polar nature. Lipids are largely insoluble in water, but are soluble in non-polar solvents such as hexane. Lipid molecules are not polymers but their non-polar nature means that they tend to group together when placed in water.

            Lipids play essential roles in cell structure and metabolism. Biochemically important lipids include the following: triglycerides, phosphoglycerides and steroids.

1. triglycerides occur in animal fats, which are solid at room temperature, and vegetable oils, which are liquid at room temperature. Triglycerides are the major storage form of the energy needed to drive reactions in plants and animals.

2.  phosphoglycerides are important constituents of cell membranes.

3.  steroids are another series of biologically important molecules.