What is the difference between grey and white matter in the brain?

Grey matter is greyish in colour because of the grey nuclei of cells and fills 40% of the brain, but consumes 94% of the oxygen.

White matter is whitish in colour because of myelin and fills 60% of the brain.

White matter is made up of long extending nerve fibers (axons) and connects various grey matter areas.

Grey matter is made up of neurons, dendrites, glial cells, synapses, and capillaries which are involved in muscle control, sensory perception, memory, emotions, speech, and self-control.

Grey matter contols how brain processing and cognition.

White matter controls how the brain functions and also controls temperature, blood pressure, heart rate.

Smokers loose grey matter at a greater rate than non-smokers.

The elderly with more grey matter have better cognitive function.

A US study has shown that there is an association in children between poverty and lower volume of grey matter.

Damage to white matter may be a sign of Alzheimers, even though Alzheimers is a grey matter disease.

Alcohol use may decrease white matter volume.

Which muscle is associated with best brain aging?

A study from Kings College, London looked at identical female twins over a ten year span. They found that the twin who had strongest leg power at the beginning of the study, also had the most amount of grey matter in the brain ten years later.

The boosting of physical activity which enhances leg strength may help with brain health as we age. 

How much fat should a person lose in order to make them look more attractive?

A study conducted by the Department of Psychology at the University of Toronto found that women and men of average height needed to loose about 3.5-4 kg (8-9 lbs) before the weight loss showed in the face.

The study shows that about twice that amount of weight needed to be lost before people were found to be more attractive.

Women needed to loose proportionally less weight then men. For women loss should be about 14 pounds and men 18 pounds.

Where is the root of happiness located in the brain?

A study conducted at the University of Kyoto, Japan found that happy people have a larger precuneus, which is grey matter located in the back of the brain between the two cerebral hemispheres. 

The precuneus is also linked to thoughts about self, memory, and the experience of consciousness.

Several studies show that meditation increases the grey matter in the precuneus.

In the study, researchers looked at two components of happiness:
1) the moment by moment experience of happiness.
2) overall feeling of satisfaction with life.