Up to 40 percent of all food is wasted at an annual cost of $218 billion, according to the Natural Resources Defense Council. “Consumers are responsible for 43 percent of this waste — more than restaurants, grocery stores or any other single part of the supply chain,” the organization says. (Salwan Georges/The Washington Post)

At the beginning of the year, a lot of folks try to figure out what to do to become better money managers.

As the good book says, their spirit is willing, but their flesh is weak. Meaning they want to change but can't overcome a lot of the things that torpedo their good intentions.

You want to stop overspending, but the call of the mall is too great. You know your grocery bill is out of control, but you keep telling yourself food is a necessity.

I would like to propose three types of financial fasts to help you on your journey to financial freedom — a food fast, a clothing fast and the 21-day financial fast.

Let's start with overspending in the grocery store. Up to 40 percent of all food is wasted at an annual cost of $218 billion, according to the Natural Resources Defense Council. "Consumers are responsible for 43 percent of this waste — more than restaurants, grocery stores or any other single part of the supply chain," the organization says.

How many times have you started home from work — or anywhere for that matter — and thought about what you had in the refrigerator to eat and decided you wanted something different?

So you stopped at the supermarket to pick up a few things. An hour later, you had a cart full of groceries. A week later, you're throwing out food.

If overspending at the supermarket is your weakness, try this food fast: Eat yourself out of house and home.

For the next month, I want you to eat all the food you have already purchased. You cannot go to the grocery store except to buy perishables such as eggs, milk, bread, etc.

In a recent online discussion, one reader decided to try this fast, writing, "After making soup, I have decided that we have more than enough food in our home. Instead of mindlessly going to the grocery store and picking up food we want to eat, we are eating what is in our home. I have multiple cans of food, frozen meals, potatoes, onions, flour, sugar, beans, etc. Why am I constantly in the store? Okay, we do need milk and eggs, but otherwise we are fine in the food department. So, I am embarking on an eat-what-I-have-at-home campaign. I figure it will save me money and declutter at the same time."

The idea of the clothes fast came from a friend, Skip Little, director of the First Baptist Church of Glenarden's Couples Ministry in Maryland.

He and his wife were cleaning during their annual household purge, and they had a revelation.

"We waste so much money on clothes," Little said. "I had 15 pairs of black shoes, 12 pairs of brown shoes and enough underwear to last me for 90 days. If I calculated how much I've wasted on clothes, I'd get depressed."

So, for the next year, Little has vowed not to buy clothes for himself. Nothing. Whenever he is tempted to shop, he plans to figure out how much he might have spent and add that amount to the money he and his wife are saving in the college funds for their two children. Or they will make extra principal payments on their mortgage.

Finally, as I do every year, I invite you to try the 21-day financial fast. For three weeks, you cannot buy anything that is not a necessity. You continue to pay your bills as usual. Of course, you still get your prescriptions and purchase only food you absolutely need. You can't eat out. You can't go to the movies. You can't get your hair done. (Ladies, did I lose you on that one?)

Do not even browse your favorite online shopping sites. Shut it all down.

The goal of the 21-day financial fast is to stop unnecessary spending.

One couple who did this fast realized they were spending more than $1,000 a month just eating out. They are now taking this savings and applying it to their credit card debt.

Several people have started Facebook groups and invited folks to do the fast together. Google "21-day financial fast" and click the link for videos you will find at http://washingtonpost.com. There is a video for each day of the fast to help you stay on track.

If you decide to try one of these fasts, let me know how you do. Send me updates on Twitter (@SingletaryM) or to colorofmoney@washpost.com.

Any one of these fasts can help you establish a habit that, once formed, will make it easier for you to become a better money manager all year long.