"Where’s the beef?!" That insistent query made for a memorable advertising campaign for a burger chain decades ago (featuring octogenarian pitch woman Clara Peller, pictured above). Now the issue about beef is not a shrinking burger patty, but whether we all should shrink our beef consumption down to zero.

As the year ended, food scientists and fast-food vendors were extolling the virtues of veggie burgers. To hear the hype, plant-based protein substitutes finally have become tasty and better than, well, sliced bread.

Still, fisticuffs all but broke out in kitchens and labs when researchers with seemingly sound credentials published a study that seemed to some to be nutritional heresy. The researchers said they had scrutinized mounds of previous work and found little scientific proof that eating less beef and pork — which the medical establishment long has endorsed — has measurable health benefits.

Here we go, again: Just as most of us are feeling a little hefty from holiday eating, drinking, and merrymaking, and while we’re deciding on our new year resolutions, what are we supposed to make of the many claims and counter-claims about diet, nutrition, and exercise? How can we lose some of that fat, get fitter, and feel better as we race through our lives at work and at home?