Triglycerides contain more metabolic energy per unit weight than glycogen because:

Triglycerides contain more metabolic energy per unit weight than glycogen because  it is water-insoluble. Triglycerides (fats and oils) are important dietary  sources of energy and they can be stored in  larger quantities than carbohydrates.  Fat also functions as a major  form of energy storage (9 Cal/g).

Carbohydrate reserves are depleted after about 1  day without food, but stored fat can provide needed calories for 30-40 days

Explanation:

Carbohydrates from dietary sources and glycogen  catabolism are used preferentially for energy  production by some tissues, such as the brain and active skeletal muscles.

Body stores of glycogen are depleted after only a

few hours of fasting, which requires fatty acids

stored in triglycerides to be used as energy sources.

Even if glycogen supplies are adequate,  resting muscle and liver cells use energy from  triglycerides because this conserves glycogen  stores and glucose for use by brain cells and red  blood cells.

a covalent bond, specfically triple bond