DEAR DR. ROACH: Would you be so kind as to send me a copy of your recommended low-carbohydrate diet? I have been trying to follow what I think it should be, but would like an expert diet on which to base my food selection. — K.H.

ANSWER: There is no specific diet I feel comfortable recommending for everyone. For people who want a lower-carb diet, I recommend eliminating processed starches, like white bread, pasta and rice, while continuing to eat vegetables and fruits. There is very good evidence that a plant-based diet, with no more than moderate amounts of animal protein, is a healthy overall diet for most people. Increasing fats from olive, nut and vegetable oils is reasonable, and there is some data to show this may help with weight control and to prevent and treat diabetes.

A dietitian nutritionist is an expert in helping create a personalized diet.

DEAR DR. ROACH: As I’ve aged, I find sleeping to be more and more difficult. When I take a product whose chief ingredient is diphenhydramine, I sleep well with no side effects, but I worry about long-term consequences. Is this safe to take daily? — T.C.

ANSWER: Most people take diphenhydramine and have no problems; however, I still don’t recommend it, especially for older people. These drugs increase the risk of falling, lead to a higher risk of motor vehicle collisions, and may cause symptoms of confusion and dry mouth. Men who take this can have decreased ability to urinate, sometimes profoundly. Although there are some studies that suggest an increased risk of dementia with use of this product, I don’t think it is likely to be a big risk, but there are still enough reasons not to use this medication for me to recommend against it.

Whenever possible, I recommend avoiding medication and focusing on behavioral techniques that have been proven effective: have a regular sleep schedule; don’t try to force sleep; avoid alcohol and caffeine near bedtime; and don’t use bright lights or computer screens before bed.

Finally, many older adults need less sleep. If you are sleeping fewer hours than you think you should be but aren’t sleepy during the day, even when doing something less interesting, then you are probably getting enough sleep.

DEAR DR. ROACH: I am a 65-year-old disabled veteran. I have lost 40 pounds and 4 inches off my waist in the past year so I can have knee surgery. But the Veterans Affairs uses the BMI as the only metric to determine body fat, so I am still categorized as “obese.”

I stand 5 feet, 10 inches with a 58-inch chest and 42-inch waist. In school I was defensive nose guard and catcher. My question: Is the BMI valid as a stand-alone metric to determine body fat? — D.W.

ANSWER: The BMI (weight in kilograms divided by height in meters squared) is a reasonable metric for obesity, and at a population level, it is a reasonably good predictor of developing diabetes and even overall mortality. However, it is certainly not perfect, and one of the most common failures is when it is applied to very muscular people. There are some people who really are “big boned,” but it’s the musculature that makes the weight go up.

Among professional American football players, even those with very high BMI levels may have very low amounts of body fat, as measured by an accurate method. In your case, the waist of 42 inches suggests that you may still have an excess of body fat, despite your excellent job of losing weight and inches off your waist.

The VA is a law unto themselves as far as determining who qualifies for procedures. Nothing I say is likely to change minds there.

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Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or send mail to 628 Virginia Dr., Orlando, FL 32803.

Dr. Roach