My wife recently brought home a horrible-tasting tub of margarine. Looking at the label on the tub, I noted the margarine was described as "fat-free."
Like butter, margarines are essentially 100 percent fat. I asked a nutritionist friend what could possibly be present in these fat-free margarines, and was told they are primarily water suspended in a mixture of monoglycerides and diglycerides and gelatin, along with some flavorings and other additives.
She added, as I had already discovered, "they taste pretty bad." They can be called fat-free because they meet the F.D.A. definition for "fat-free" labeling - that is, they contain less than 0.5 grams of fat per serving.
Since the tub incident, we have received a number of coupons for savings on fat-free margarines, and my wife tells me the supermarkets sell several of them. These margarines (though I hardly think they deserve the name) are certainly heart-healthy and contain fewer calories than regular margarines.
If you can stand the lack of expected taste and flavor, they could serve as a reasonable stand-in for the real thing at the table.
In contrast to fat-free margarines and assuming the labels are accurate, I can endorse margarines labeled "trans fat-free." The absence of trans fats should make these margarines more heart-healthy than the regular ones. Trans fats not only raise the atherogenic LDL cholesterol but also lower blood levels of protective high density lipoprotein (HDL).