They say weight loss is an investment. Perhaps that's intended as some sort of uplifting figure of speech, but finances really do play a large role in weight management and fitness.

Believe me, I know. I've spent the last three years trying to lose the 50 pounds I put on while I was in college. It was a long, frustrating seesaw, but now I've lost those 50 pounds (and seven more), and I'm in the best shape of my life. I've also spent literally thousands of dollars getting to this point. No surgeries or expensive prescriptions -- just all the little expenses that come with the journey and add up over time.

Sure, losing weight is an investment, but it costs a lot to gain weight, too. Let's look at the costs of some unhealthy habits:

• Eating out three or more times per week: $50/week

• Habitual snacking (anyone else stop at Starbucks everyday for a 600-calorie, $4 beverage?): $20/week

• New clothes: $500 is a conservative estimate for the cost of a basic new wardrobe, and that's for every time you go up a size.

• Medical expenses: A few extra insurance co-pays in the short term; numerous health risks and the associated gigantic medical bills in the long term.

A conservative estimate indicates that going up, say, two sizes in one year, would cost in the neighborhood of $5,000!

Our metabolisms do slow down as we get older, but few people gain lots of weight in a short time without adding calories to their diet. In my case, I was not only buying more food, I was also eating out more. This is an expensive habit to begin with, but also very unhealthy. The reason that restaurant food is so tasty is that it's bathed in butter. I was spending more money per meal on myself while growing right out of the clothes that had fit me for years.

There's a bit of denial that comes with gaining weight, too. You know you're getting bigger, but you assume you'll plateau; the gain will stop; it's just five pounds. So you go ahead and replace your wardrobe with clothes the next size up. But you don't change your habits and you keep gaining weight. Those new clothes last you maybe a few months, but then you have to replace them, too.

While I spent lots of money on food and clothes, the biggest expense of my weight gain was medical. I wasn't healthy anymore, and I was getting sick, injured, and depressed pretty frequently. All of this was a huge source of stress and misery for me, and of course I wanted to reverse course, but it's really true that you can't lose weight until you're ready.

Sure I would've loved to lose 50 pounds, but it took a while for me to hit my breaking point. My efforts up until then had been half-hearted at best. But when the needle on the scale began hovering dangerously near the 200-pound mark, I knew I was never going to let it cross that line. And so began my investment in weight loss.

Think back to our $5,000 estimated annual cost of weight gain. If you've gained weight recently, think about the habits that contributed to your weight gain. Did you eat out more? Are you in denial about how many calories your "coffee" runs are costing you? Did you choose to spend money on cabs or gas for your car when you could have walked? Now think about the consequences of these decisions. Yes, you gained weight, but you also had to buy new clothes, and you probably got sick more often and spent more money on medical treatment. Add it up now. How much are your choices costing you?

Keep reading this series, with the weight loss investment and how to count up the dividends.