There’s good news and bad news here, though overall it seems the scales tip in lard’s direction. Calorie-wise, lard has more of them, about 15% more, which makes a lot of sense when you consider that butter is about 15% water. Compositionally, though, there are certain factors that make lard more desirable, at least based on the (ehem) current thinking of many researchers and nutritionists.
Fat, you see, is not a uniform substance. It’s made up of lipid molecules of many different configurations. As I’ve mentioned many times before, lipids are basically “E”-shaped molecules, consisting of a “backbone” of glycerol and three fatty acids. The fatty acids attached to the backbone are all different from one another, and more than that, vary from molecule to molecule. Where molecules in a fat have similar structures, they will often form solid crystals. Others won’t. It’s this mixture of solids and liquids that gives fats like butter and lard their semi-solid consistency.
As I’ve mentioned in previous posts on fats, fats that are saturated tend to be firm at room temperature, those that are unsaturated tend to be liquid (for a helpful metaphor on that subject, see this post on shortening and oil). Unsaturated fats, it’s thought, are better for you, said to have the effect of raising the so-called “good cholesterol” in the body.
Butter has unsaturated fats in its lipid mix, but it has more saturated fats. Lard is just the reverse, more unsaturated fats than saturated fats, which makes it a “better fat” as the present-day thinking goes. It’s even said that the saturated fats that are present in lard have a neutral effect on the “bad” cholesterol in the body. I don’t know about that. Come to think of it, I don’t know about any of it, for according to the results of the Women’s Health Initiative study, none of it really matters to your health anyway. But what are you gonna do?
Personally, I don’t think it really matters which fat is “better for you” and which fat is “worse”. Splitting hairs over it, to me, makes no sense whatsoever. Eat happily but moderately, and exercise, and I can’t see how a body can go wrong.