They’re back … but only until St. Patrick’s Day. If you’re a lover of McDonald’s Shamrock shakes, their limited-time availability is both a curse and a blessing. On the one hand, you may get withdrawal symptoms come March 18^th. On the other hand, you and the scale will be thanking you once you’ve put your addiction to rest for the rest of the year. That’s because these frosty mint smoothies are loaded with fat and calories.

Indeed, a 21oz. serving of this St. Patty’s Day delight isn’t so delightful for diligent Bootcampers. Consider these nutritional facts before indulging one too many times: That 21-ouncer contains 18 grams of fat and a staggering 740 calories.

So how do you get your minty holiday kicks without destroying your Bootcamping efforts? You make your own Shamrock shake at home with low-cal, low-fat ingredients, that’s how. And if you’re not a fan of the green mint flavor? You can always modify this recipe with a different flavor and color. (Surprise alternative: Hershey’s chocolate syrup is fat free!)

(Virtually) Guilt-Free Shamrock Shake

2 cups of vanilla frozen yogurt (Look for the no sugar added version to save even more calories.)

1 ¼ cups of 2% milk (If you don’t mind a thinner version, opt for 1% or skim milk instead. You’ll save even more fat grams that way.)

¼ teaspoon of mint extract (To get that Shamrock shake flavor, make sure it’s mint and NOT peppermint.)

8 drops of green food coloring (Optional, but adds to the festive fun.)

Add all ingredients to your blender then blend on high speed until smooth. Makes two 12 oz. servings.