There is a natural parallel between losing weight and saving money.

For the past several months, CB has been on a weight loss journey. In the middle of January, I joined him. True, we want to look good for the wedding (because there’s nothing like having your appearance captured by pictures that will last forever to give you a kick in the pants), but more importantly we want to establish good eating habits and exercise habits to carry us far beyond the Big Day. CB lost 50 pounds in eight months, going from a 38-inch waist to a 32-inch waist. I had a modest-sounding-but-still-signficant-to-me 6 pound weight loss, trimming an inch around my waist.

Watching CB lose weight and then working at it myself, I realized that there are so many lessons that losing weight have taught me about saving money.

1. It’s about understanding the numbers AND taking action.

Losing weight and saving money are math problems. To lose weight, you need to create a calorie deficit – eat fewer calories than what your body needs to maintain its current weight. To save money, you need to spend fewer dollars than you earn. Both cases can be boiled down to a case of simple arithmatic: dollars in vs. dollars out, calories in vs. calories out.

But THEN you throw in human behavior, and it just all goes out the window! Plenty of people understand that eating unhealthily and sitting all day will encourage weight gain, just as plenty of people understand that if you spend more than you make, you will run into debt. But as anyone as ever tried to lose weight or save money (*raises hand*) would tell you, it’s one thing to know the math. It’s another thing to make the not-so-fun decisions (choosing an apple over a chocolate muffin, trading a loft apartment for room in someone else’s house) that will allow you to achieve the desired results.

2. You can’t out-train a bad diet, and you can’t out-earn bad spending.

Watch this video on why you CANNOT out-train a bad diet <—- one guys runs at a pace of 11 miles per hour and burns 40 calories in a few minutes. In the same amount of time, his buddy consumes almost 1,000 calories in pizza and soda. In the same way, I’d say that you can’t out-earn bad spending. Of course, if you are rich like Bill Gates is, it is quite difficult to imagine how you can ever spend all that money if you just kept a portion of your wealth in income-producing investments. On the other hand, we’ve all heard stories of some very wealthy people – professional athletes, Hollywood stars, famous photographers, etc. – who have to live in reduced circumstances because they spent beyond their means.

Making a high income is important, it’s one side of the equation. But it’d be pretty darn difficult to earn enough money to support a life of indiscriminate spending. Focusing on earning without examining your expenses is akin to trying to lose weight while filling your diet with sugary drinks and fried foods. When I saw that video, I felt a lightbulb switch on…. which brings me to the 3rd lesson I’ve learned.

3. You can’t manage what you don’t measure.

If you want to lose weight, you need to measure what you are eating. If you want to save money, you need to measure how much you are spending. Trying to lose weight and save money means that you are by definition changing the status quo – so you HAVE to do something differently in order to see results. Your current diet isn’t working. Your current spending isn’t working. Otherwise, you would have already gotten the results that you wanted.

CB and I both track our calories. He does it on a piece of paper, I do it with the app MyFitnessPal. Once I started seeing results with MyFitnessPal, I realized that I needed to do the same thing with my finances. I’ve tried out several expense tracking applications recommended by readers, and for now I’ve been entering my data into iXpenseIt – but I’m open to other suggestions! Measuring my progress allows me to 1. stop deluding myself on how much I am really eating or spending, and 2. show me where I am going overboard. Incidentally, it’s the same with both expenses & calories: eating out… coincidence? I think not!

4. Know what’s worth it, and what isn’t.

We all have limited resources – calorie-wise or dollar-wise – so it’s important to figure out what purchases or meals are “worth it.” After almost two months of paying attention to my diet, I have developed a repetoire of meals that I know are worth the giant caloric intake: fried chicken over oily sticky rice from my favorite Thai takeout (800-1,000 calories), flourless chocolate tort from the Capital Grille (734 calories), curry ramen at the local noodle house (650-700 calories), scones that CB’s sister makes (300 calories per scone, but I always eat 2-3 in a sitting!), etc. I also know what ISN’T worth the extra calories, so I don’t eat those foods.

When it comes to spending, I am working on the same mentality. Tango lessons for $15 a pop is worth it to me, buying 2 e-books for that same price is not. I have enough lotions to keep me moisturized for a year, so even though the new bottle is on sale, I am not going to buy it. All that money I’ve saved can go towards something that I really want, that is really worth my dollars – things like travel, retirement accounts, facials, etc. By spend money on what is important to you, and ruthlessly cutting expenses on all the rest, you’ll be able to gain more enjoyment from your dollars AND prepare for a financially sound future.

5. Plan ahead and build in a cushion (and when you slip up, get back on track).

We won’t eat perfectly 100% of the time and we won’t spend perfectly 100% of the time. By planning ahead and building a cushion, however, I can mitigate the impact of a bad diet decision or unexpected expense. So when I know I am going to spend Friday night with a giant bowl of the delicious chicken mentioned above, I try to shave a hundred calories off every day in the beginning of the week. When I know I have to pay for tuition deposits in a few months, I try harder to squirrel some more nickels so that when the day comes, the bill wouldn’t be such a shocker. (But I think it still will be).

Despite our best plans, though, we make mistakes and veer off track… because life happens. The important thing is to not let a bad day turn into a bad week, and a bad week turn into a bad month, and so on. When I was in Las Vegas, all my discipline went out the window and I enjoyed far more culinary delights than I should have. But when I came back from that trip, I told myself, “OK, now you have to get back on track!” And I did. When I was visiting all these business schools during interview season, I didn’t always choose the cheapest flights or car rentals. I chose convenience, and that was OK. But now that I have more time to look for flights for my honeymoon and other trips, I take longer to search for deals and make my purchases.

6. It’s not a quick fix, it’s a way of life.

One night, CB came to me with a mournful look on his face and said, “you know, I’ll have to eat like this for the rest of my life.” I looked at him and said, “me too. But that’s OK. We have to make healthy eating a lifestyle. It’s GOOD for us!” (the truth is at that moment I was really, really craving a giant piece of chocolate fudge). When I think back to how and what we used to eat, I realized that that’s not a sustainable way of eating. We had no concept of moderation, we underestimated the calories in our foods and overestimated the calories burned through exercise, we ate whatever we wanted, whenever we wanted, and usually what we wanted were NOT salads or grilled veggies. This new phase in our life isn’t a short-term fix. It has to be for life.

The truth is we can’t eat whatever we want – unless you are one of those rare souls who truly prefer tofu over fried chicken – and we can’t buy whatever we want. Nothing you do will change those facts. If you try to deny it, you are only going to dig a deeper hole for yourself, in terms of bad debt or bad health, or both.

7. Don’t just rely on sheer willpower, figure out a system instead.

Willpower is a limited resource, in fact, studies have shown that when we expand willpower on certain things, other goals fall by the wayside. That means if you are trying hard to save money, you may be lackadaisical with eating healthy. That’s why it’s helpful to figure out a system that will help you make the right decisions, WITHOUT using your limited reservoir of self-discipline. When it comes to finances, it’s paying yourself first. When it comes to losing weight, it might be putting gym clothes in your car (check), stocking your fridge with low-calorie treats for when you get a sugar craving (and by you, I mean me), and making the decision NOT to go out to eat instead of relying on your self-discipline to order the lite dishes.

8. When you see results, all the hard work will be worth it.

This one’s self-explanatory. When we look at our retirement accounts or reminisce about the trips we have taken, I don’t think about the clothes I didn’t buy or the restaurants I didn’t go to, and I don’t miss the luxury apartment that I visited but never leased. I bet CB doesn’t mind that he got an old Honda for $4,000 instead of a new Acura for $24,000. And when we see how we look, and feel, now, we don’t miss the fact that we can only eat my beloved Thai fried chicken once a month instead of twice a week. The results are worth it.

Have you found similiarities between losing weight and saving money? Which one is harder? (and if there’s anything you learned from this post… it’s that I have an addiction to fried chicken).

This post has been featured as an Editor’s Pick in Carnival of Personal Finance