The phrase "to avoid a mess" means to take action or make a decision in order to prevent a situation from becoming chaotic, confusing, or difficult to handle. Full definition
If your chief concern is flavor and want to avoid messing with the nutritional content of your shake, almond extract works great. (blog.nkdnutrition.com)
To avoid messing up your testosterone production, try to avoid late night sugary snacks at all costs, or at least replace them with low - carb fruits. (fitnessandpower.com)
Avoid the mess of frying oil and go for a quick oven - roast. (epicurious.com)