The energy equation
Q If I eat 2,000 calories a day and 80 grams of protein and expend 2,500 calories a day in exercise, will the extra 500 calories come from stored fat or converted protein?
A If you burn up more energy than you eat, you will lose stored fat. Once you have used up all your stored fat, you burn muscle. Your basal metabolic rate is the rate at which you burn up energy just by breathing and keeping your body ticking over.Even if you do no exercise, most grown men burn up around 1,500 calories a day or more. Exercising burns up extra energy, but not as much as many of us think, which explains why the odd session at the gym doesn't turn us into sylphs. To burn an extra 500 calories, you need to run five miles or do something equally aerobic - and eating one cheese sandwich will replace those 500 calories at a stroke.
Whether you eat fat, carbohydrate or protein-rich food doesn't really matter from a calorie point of view. Any excess intake is still stored as fat, whatever you put in your mouth.
What are my chances of getting breast cancer?
Q I have recently had a benign breast lump removed. The biopsy revealed that I have atypical lobular hyperplasia; the doctor told me not to worry about this, as it increases my chances of breast cancer by an "infinitesimal" amount. I have since done some research and it seems that the condition in fact increases a woman's chance of developing breast cancer by four or five times - up to 10 times if she has a family history of the disease.
Would a woman in my position benefit from taking tamoxifen and/or having regular (annual) mammograms? I am in my mid-40s, pre-menopausal and do not know my family history.
A The worry about breast cancer is real for all women, as one in 12 of us will get breast cancer. Once you find a lump, this anxiety obviously increases. And while you can be reassured by the fact that your lump is not cancerous, it is true that atypical hyperplasia does increase your risk. Hormonal changes before the menopause make women in their 40s particularly prone to these changes.
An American website provides a tool to allow you to calculate your risk. Making a few assumptions, such as that you don't have a genetic tendency to breast cancer, I used the tool to find out how much your risk is increased. The risk for a woman of your age over the next five years increases from 0.7% without hyperplasia, to 1.2% with it. That means a 99% chance of not getting it. You should discuss this with your specialist, but it may be that the increased risk is so small that you would be best advised to avoid extra tests or drugs. The risk-calculation tool is at http://bcra.nci.nih.gov/brc
Is my droopy eyelid going to kill me?
Q I have read that people who suffer brain aneurysms often have a drooping eyelid. I am 55 and have had a drooping eyelid for as long as I can remember. Should I be worried?
A Drooping eyelids are known as ptosis, and longstanding ptosis is rarely a sign of anything serious. Babies are sometimes born with ptosis as the muscles that raise the eyelid are weak. The commonest reason later in life is ageing of the eyelid muscles. Some muscle and nerve diseases can cause a ptosis so if you develop ptosis out of the blue, it needs to be investigated. Since you've had yours for ages and assuming you are otherwise well, I wouldn't worry about it. Cosmetic surgery can work but it's fairly major and you'll have to pay for it unless you can prove that it is affecting your vision.
· These answers are intended to be as accurate and full as possible, but should never be used as a substitute for visiting a doctor and seeking medical help. If you have a question for Dr Robinson, email firstname.lastname@example.org or write to her c/o The Health Editor, The Guardian, 119 Farringdon Road, London EC1R 3ER. She regrets that she cannot enter into personal correspondence.