Margarine is not lower in calories or healthier than butter.  

I really love butter.  If you are like me, you like butter on just about anything but ice cream.  You can add a dab to a potato, toast, pasta, sweet potato or just about anything.  You probably have heard the conflict between butter is healthy or is it unhealthy.  Heck,  I am just as confused as you are so what is the truth.  You probably feel guilty about adding that golden spread to your plate and you have probably been told that margarine is healthier, but you do not need to conflict anymore.  

Butter has been a central item of many meals for Americans.  Heck, there is nothing like a pad of Danish butter on a German roll.  Butter came under a great deal of criticism over the years.  I can tell you that I have always been told as a physician and a patient that its high levels of saturated fat were associated with increased heart disease risk.  What I can tell you is that may not be entirely true.  Over the last 10-20 years, this opinion has been filled full of holes more times than the zombies in a B rated film.  So what

So what is the truth? Margarine is a fatty alternative to butter that is made from vegetable oil and has flavoring and coloring.   Often these additives are artificial.  Vegetable fat is liquid in its natural form.  The truth is that margarine has a different type of fat but the calorie count is almost identical.  Margarine is often lower in saturated fat than butter, but it lily has hydrogenated fats or additives to make it solid.  The most recent research points to the fact that saturated fat is not as unhealthy as we once thought.  Saturated fats are not associated with all-cause mortality, cerebrovascular disease, coronary artery disease, ischemic stroke, or type 2 diabetes​[1]​.  Trans fats are associated with a higher risk of death.

So what about calories?  Butter and margarine are essentially the same when it comes to calorie content.  They are both essentially 100% fat in composition.  There is some variety among brands.  See the table below.  

The bottom line:  There is no evidence that using margarine instead of butter cut the chances of having a heart attack or developing heart disease.  Butter and margarine essentially have the same number of calories.  Check the label for hydrogenated oils.  I recommend that you find a spread you like and use it.  Personally, I use Brummel & Brown buttery spread because I like the flavor and it has fewer calories than butter, but I could easily switch to whipped butter.   Healthier alternatives to butter or margarine exist to include ones that contain olive oil and other plant-based spreads.   You do not need to avoid buttery spreads the next time you have some toast for breakfast.