You’ve heard the advice a million times: Slow and steady wins the race. But then, you’re scrolling through social media and see a before-and-after photo of an acquaintance who lost double-digit kilos in days—and has a link to exactly how they did it. It’s tempting...
Their efforts may have earned them a smaller jeans size and plenty of clapping emojis, but their method might not be cause for celebration. While it’s true that some deprivation diets can lead to short-term success on the scale, experts say that quick weight loss is often unsustainable and, in many cases, unhealthy.
“It seems like everyone who wants to lose weight wants to lose it fast,” says Cheryl Mussatto, dietitian. That said, if you want to maintain your health and keep weight off, research suggests that a safe rate of weight loss averages ½ to 1 kilogram per week. Here’s why:
1. Restrictive dieting to speed up weight loss can leave you hungry (and hangry)
At first, ultra-restrictive rules that form the building blocks of most extreme weight loss plans may briefly cause your body and brain to feel better than it did before you jumped on the bandwagon—particularly if your old diet lacked balance or wholesome ingredients. “A so-called normal diet often consists of unhealthy, processed foods,” explains Dr. Sari Fine Shepphird, PhD, a Los Angeles-based psychologist. And when you change it up? “Feeling an initial rush of wellbeing isn’t entirely off the mark,” she confirms. But she doesn’t condone cleanses or crash diets, because any serotonin rush you might experience at the onset of your crash dieting is bound to be temporary.
Soon enough, extremely low-kilojoule diets can bring on side effects like nausea, constipation, insomnia, and irritability, according to Mussatto. And don’t be surprised if you also find yourself with a splitting headache, low energy, and a bad mood after comfortably zipping up a dress that’s been feeling tight.
Oh, and as for “hanger,” the moodiness that kicks in when you’ve eaten too little? It’s real: A study published in the journal Emotion found that hunger may cause people to experience a negative, antisocial emotional state.
2. Fast weight loss strategies aren’t sustainable in real life
Quick weight loss strategies are not sustainable in real life. Trying to stick to a restrictive or fasting diet while navigating social situations like meals with partners, family, or friends can lead to constantly having to decline food and feeling stressed about what you can eat. This situation can be challenging logistically and emotionally. Moreover, deprivation can eventually lead to overeating once the crash-diet phase is over.
Bottom line: “Long-term, most people who try quick weight loss plans may lose some weight, but more times than not, they fail and usually struggle to keep weight off,” Mussatto says.
3. Fast weight loss plans can cut out nutrients you need
Ulta restrictive diets that promote quick weight loss by eliminating entire food groups or macronutrients like carbohydrates, may cause you to miss out on essential vitamins and minerals that your body needs, according to a study published in Nutrients. Deficiencies in certain micronutrients can negatively impact your immune system, energy, mood, and even your sleep patterns. And what good is weight loss if you end up physically and mentally worse for wear?
4. Taking the wrong DIY weight loss approach can set your body up for trouble
It’s always smart to speak to your doctor before trying any new eating program. And when you do, they’ll likely warn you that there’s a general lack of research surrounding certain fad diets’ safety. It could be why experts recommend against trying common ones like the ketogenic diet.
The risks are real: In a study published in the International Journal of Obesity, researchers found that very low-kilojoule diets may cause a deterioration in heart function in some people.
In general, remember that whether or not a fad diet lowers your weight, the number on the scale doesn’t tell the whole story of your health.
5. Fast weight loss fixes can be unnecessarily expensive
Many supplements and specialised weight loss foods come with a hefty price tag. But do they actually work? Generally speaking, the answer is no—or at least not for the long term. According to Mussatto, a reliable method for achieving healthy and sustainable weight loss considers several factors, including food tracking, moderation, and prioritising whole foods over processed ones. Since there's no magic tea, shake, or pill that can replace these fundamental principles, investing in them for quick fixes is simply not worth it. To save both your wallet and your health, start by making gradual changes to your diet, such as swapping sugary and expensive smoothies, and soft drinks for water and unsweetened tea.
The bottom line
“Any time a diet sounds too good to be true, it often is,” Mussatto says. For sustainable weight loss, try a program that helps you establish healthy habits and allows you to go out to dinner and enjoy your favourite foods—even if it takes you a bit longer to reach your weight loss goal.