Question: Does muscle weigh more than fat?

Answer: Yes, muscle is denser than fat so if the volumes were equal, muscle would weigh more.

This may account in part for two people who are the same height and weight looking so different -- the person with more muscle mass might look more trim.

Question: I dread coming back to school after the holidays.

Last year I was really depressed in January and had a hard time concentrating on the new semester.

By Valentine's Day I was OK, but it was bad for a while. Is it true that people's biorhythms change in the winter months?

Answer: If it is any comfort, you are not alone. Being a little "down" after the holidays is a common reaction.

There are many possible causes, and some may be easier to address than others.

Basically you have had two to three weeks away from academic work; you have had more free time for fun activities; perhaps you haven't had to stick to a rigid schedule; maybe you have been eating more than normal; or perhaps you have enjoyed the reassurance and comfort of being at home with family and old friends.

Getting back to the reality of getting up early for classes, researching reports and papers, studying for tests, and even having to share a bathroom again with roommates can all be a letdown.

In answer to the other part of your question about people's biorhythms changing in the winter months, there is a condition called Seasonal Affective Disorder (SAD).

Approximately 5 percent of Americans are negatively affected by the lack of sunlight in the winter months.

They may have less energy, be less productive, and generally feel down in the dumps.

The good news is that there are several positive things people with SAD can do to get more exposure to light in the winter.

They include keeping their living area bright and getting outdoors as much as possible.

For example, a long walk with a friend on a winter afternoon can be invigorating.

In more serious cases, various types of therapy may need to be explored with a health care professional.

One caution -- tanning booths are not the answer unless you want to run the risk of skin cancer!

UVA rays from tanning beds or sun lamps can be more intense than natural sunlight.

Twenty minutes in a tanning bed can equal several hours in the sun. This may seem like a quick fix, but you should weigh the risks of harmful UVA rays.