You gotta have fat, on that we all agree. Our bodies need a certain amount of fat in order to function properly. But how much? And what kind? That's where the consensus breaks down.

Studies that focus on the benefits of low fat versus high fat diets are outdated, because we now know that there are good fats and bad. But the perplexed layperson (i.e., me) has a hard time getting a straight answer when it comes to how much fat is really good for us, and which fats are the most beneficial.

One thing is clear; our grandparents slathered butter on their bread, cooked their meals in lard, drank whole milk, ate eggs and bacon as often as they liked, and seemed, overall, to be none the worse for it.

Now, our larders are lard-free And yet, our own backsides are fatter than ever. And as we've grown fatter, fat itself has become a bit of a scapegoat.

Here, LIME airs the views of the low fat advocates versus the good fat faction.

Pro low fat:

Dr. Dean Ornish has been preaching the benefits of a low fat diet for more than a decade. In Eat More, Weigh Less, Dr. Ornish's prescription for a healthy heart precluded all kinds of meats, even chicken and fish, as well as nuts, olives, avocados, and "any commercially available product with more than two grams of fat per serving."

Dr. Ornish dismisses a recent study that suggests a low fat diet offers no protection against certain cancers or hear disease as being fundamentally flawed, in part because the women who participated were supposed to reduce their fat intake to 20% of their daily calories but could only manage to reduce it to 29%.

"Small changes in diet don't have much effect on preventing heart disease and cancer in those at high risk," Dr. Ornish insists.

However, critics of Dr. Ornish's low fat approach say that this only shows how difficult and unrealistic an extremely low fat diet is for most people. Dr. Ornish once advocated a diet containing no more than 10% fat, which, if you're consuming 2000 calories a day, would limit you to, say, one and a half teaspoons of olive oil, or 1/8 cup of nuts.

While Dr. Ornish now concedes that "the omega-3 fatty acids found in salmon, mackerel, halibut, walnuts and flax may reduce your risk of a heart attack by 50 percent or more," he remains convinced that a diet significantly lower in fat than the typical American diet is the best protection against disease.

Pro Good Fat:

Proponents of a Mediterranean style way of eating, rich in good fats, believe that diets based on deprivation just don't work. Books such as the Sonoma Diet and Canyon Ranch Cookbook emphasize that we need the flavor and "mouth feel" that good fats provide to create truly satisfying meals.

Dr. Andrew Weil recommends that nearly a third of the calories we consume should be in the form of fat. "In my opinion, telling people to avoid fat is as misguided as telling people to avoid carbohydrates... when food has too little fat, it very often just doesn't taste good, " he points out in The Healthy Kitchen. "The problem is not to get the fat out but to avoid the bad fat and get the good fat in."

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So which fats are good and which are bad? Both Dr. Ornish and Dr. Weil agree that trans fats, found in many chips, crackers, and fast foods, are bad. Saturated fats in meat and dairy products are likewise to be shunned, while monounsaturated fats from avocados, nuts, seeds, and olive oil, are considered ideal. Omega 3 fats, which are polyunsaturated, are regarded as essential for good health.

Do you distinguish between good fats and bad when you read the labels on food products? Do you believe it's healthier to keep the fat in your diet to a minimum, be it good fat or bad? Who would you rather have dinner with, Dr. Ornish or Dr. Weil?