Betting On Your Own Weight Loss: DietBet, HealthyWage and stickK Explained

What if your diet came with real money on the line? A small industry has grown up around exactly that idea. You stake cash on your own weight loss, and you either win it back with a profit or lose it. Here is how the three best-known options work, who they suit, and the traps to avoid.

Why betting on yourself works at all

Most of us know what we should eat and how often we should move. The problem is following through when the reward (a slimmer, healthier you) is months away and the temptation (pizza, tonight) is right in front of you. A bet changes the maths of the moment. Skipping the gym is no longer free; it might cost you money. Behavioural economists call this a commitment device, and the reason it works, loss aversion, has its own article: why money on the line helps you stick to a diet.

There is some evidence behind it. In a 2008 trial published in JAMA, Kevin Volpp and colleagues at the University of Pennsylvania offered 57 adults with obesity either a lottery-style incentive or a deposit contract, where participants put their own money down and got it back with a match if they hit their targets. After 16 weeks the incentive groups had lost around 13 to 14 pounds on average, compared with about 4 pounds in the control group. The catch: by seven months, after the incentives stopped, much of the difference had faded. Money is a powerful starter motor. It is not a whole engine.

DietBet: the shared pot

DietBet, run by the US company WayBetter, works like a pooled wager among strangers. In its classic four-week game, every player pays the same stake into a pot, and everyone who loses at least 4 percent of their starting weight by the end splits the pot. Players who miss the target lose their stake, which is where the winners' profit comes from.

The payout depends on how many people succeed. If most players hit 4 percent, each winner gets back their stake plus a modest profit. If many players drop out, the profit per winner rises. In reported games, winners have typically ended up with somewhere around 10 to 30 percent more than they put in. The sister app StepBet applies the same model to daily step counts, which is useful if you would rather bet on movement than on the scale.

Health check: 4 percent in four weeks works out to about 1 percent of body weight a week, which sits at the upper end of the usual advice of 0.5 to 1 percent a week. For someone with plenty to lose it is achievable with sensible eating and activity. For someone close to a healthy weight it may push towards crash dieting, which is not worth any pot.

HealthyWage: the bookmaker model

HealthyWage works more like a bookmaker setting a price on your personal challenge. You choose how much weight to lose (at least 10 percent of your starting weight), over how long (6 to 18 months), and how much to wager each month. A prize calculator then quotes what you would win if you succeed, with advertised prizes of up to $10,000. Bigger goals, shorter timelines and larger stakes mean bigger prizes.

• Weigh-in: you verify your starting and finishing weight by video, or through a form signed by a health professional such as a doctor or gym staff member.
• Outcome: reach your goal by the deadline and you are paid your prize. Miss it and you lose what you wagered.
• Teams: HealthyWage also runs team challenges and workplace programmes, which pair the money with social pressure (more in office fitness challenges and friendly wagers).
• Tax: prize money can count as taxable income, so keep records.

Like a bookmaker, the company prices the bet so that, across all players, the stakes of those who miss their goals cover the prizes of those who hit them. That is not a scam; it is simply how any wager is priced. It does mean your job is to be in the group that finishes.

stickK: the commitment contract

stickK was founded in 2007 by Yale economists Dean Karlan and Ian Ayres, with Jordan Goldberg. It is less a bet against other people than a contract with yourself. You set a goal and a deadline, for example "lose 0.5 kg a week for 12 weeks" or "go to the gym three times a week", and you can choose to put money at stake.

If you fail, the money goes wherever you chose in advance: a friend, a charity, or an "anti-charity", an organisation you actively dislike. That last option is the site's most notorious feature. Few things get you to the gym on a rainy Tuesday like the thought of funding a cause you oppose. You can also nominate a referee, a friend who confirms whether you really hit your goal, because honest self-reporting is the weak spot of any commitment contract.

	DietBet	HealthyWage	stickK
Who you bet against	Other players in the pot	The house (prize calculator)	Your own contract
Typical length	4 weeks to 6 months	6 to 18 months	Any length you choose
Can you profit?	Yes, a share of the pot	Yes, a quoted prize	No; you only avoid losing
Where lost money goes	To the winners (after fees)	To the company and prize fund	To a friend, charity or anti-charity
Best for	A short, social kick-start	Big, long-term goals	Any habit, not just weight

Is it gambling?

These services are generally treated as contests of skill rather than games of chance, because the outcome depends on your own effort rather than a card or a spin. That is a big difference from a casino, where the house edge is fixed and no amount of effort changes it. Availability and rules still vary by country and state, so check the terms where you live. And remember that the money is a tool: if the stakes would cause real hardship, they are too high.

How to bet on yourself sensibly

• Pick a realistic target. Around 0.5 to 1 percent of body weight a week is a common guide. Talk to your doctor first if you have a medical condition or a lot of weight to lose.
• Stake an amount you would hate to lose but could afford to. It needs to sting, not hurt.
• Never manipulate a weigh-in. Dehydrating, sweating it out or skipping meals before a weigh-in is dangerous, and the weight returns the next day anyway.
• Plan for after the deadline. The Volpp study is a reminder that results fade when the incentive stops. Use the bet to build habits (see the science of never missing a workout) and line up the next goal before the first one ends.
• Judge the trend, not one day. Daily weight swings are noise. Our guide to weight-loss plateaus explains why.

Used well, a weight-loss bet is one of the few wagers where the odds are genuinely in your hands. The best outcome is not the prize money. It is reaching the deadline with habits that no longer need a bet to keep going.

This article is general information, not medical advice. Check with a doctor before starting a new diet or exercise programme, especially if you have a health condition.