Analysis: Aggressive, short-term diets might be seductive and deliver quick wins, but they are unsustainable and rarely deliver lasting success
Every January, the same story plays out. We make bold resolutions, fuelled by optimism and the promise of a "new year, new me." Then, the diet industry swoops in with its glittering offers. Lose 10 pounds in 10 days! Drop two dress sizes before February! It sounds tempting, doesn't it? After all, who wouldn’t want fast results?
But the truth is: if it sounds too good to be true, it probably is.
Why we’re drawn to quick fixes
There’s a psychological pull to aggressive, short-term diets. They promise early gratification in a quick win that feels motivating. Seeing the scales drop fast can feel like proof that we’re on the right track. In fact, research shows that early success can boost confidence and commitment.
But these wins are almost always temporary. Rapid weight loss often comes from water and glycogen depletion, not fat. When the diet ends - as it inevitably will - weight regain is common. Why? Because these diets rarely teach sustainable habits. They’re built for speed, not endurance.
We need your consent to load this rte-player contentWe use rte-player to manage extra content that can set cookies on your device and collect data about your activity. Please review their details and accept them to load the content.Manage Preferences
From RTÉ Radio 1's Today with Claire Byrne, is diet losing out to slimming drugs?
The problem with aggressive diets
Aggressive diets typically reduce calories to extremes, sometimes below 800 kcal per day. That’s less than half of what most adults need just to function. While this might trigger rapid weight loss, it also triggers metabolic and psychological backlash.
· Metabolic slowdown: Your body adapts to scarcity by burning fewer calories. This makes future weight loss harder.
· Muscle loss: Severe restriction often leads to loss of lean muscle tissue, which further reduces metabolic rate.
· Psychological strain: Hunger, fatigue, irritability - these aren’t great companions for building healthy habits.
Then there’s the rebound effect. When the diet ends (because when you are on a diet, you always eventually come off), appetite hormones surge, cravings intensify, and old habits creep back in. The result too often is weight regain, often with interest.
We need your consent to load this rte-player contentWe use rte-player to manage extra content that can set cookies on your device and collect data about your activity. Please review their details and accept them to load the content.Manage Preferences
From RTÉ Radio 1's News at One, Oxford University researchers found that people who stop using anti-obesity jab regain all the weight they lost within 20 months on average
The boring advice that works
Here’s the part no one wants to hear: the strategies that actually work are… boring. They don’t promise overnight transformation. They don’t come with flashy hashtags or celebrity endorsements. But they’re backed by decades of evidence.
· Eat less, move more: Energy balance still matters. Reducing calorie intake modestly - by 300–500 kcal per day - combined with physical activity creates sustainable progress.
· Watch portions: You don’t need to ban carbs or demonise fat. Simply eating with intent and controlling portions can make a big difference.
· Pair diet with exercise: This is the double impact. Exercise preserves muscle, boosts metabolism, and improves mood.
· Be realistic: Body weight, shape, and composition change slowly. Aim for 0.5–1 kg per week, not 5 kg in five days.
· Be kind to yourself: Progress isn’t linear. There will be plateaus and setbacks. That’s normal.
Rome wasn’t built in a day - and neither is a healthy body.
We need your consent to load this rte-player contentWe use rte-player to manage extra content that can set cookies on your device and collect data about your activity. Please review their details and accept them to load the content.Manage Preferences
From RTÉ Radio 1's Today with Claire Byrne, how much protein do you need in your diet?
Why sustainability beats speed
It can be helpful to think of weight loss like building a house. Crash diets are like throwing up a cardboard shack overnight. It may look impressive for a moment, but it won’t withstand the first storm. Sustainable habits are the bricks and mortar - the foundation that lasts.
When you focus on gradual change, you’re not just losing weight; you’re learning skills. How to plan meals. How to navigate social eating. How to cope with stress without turning to food. These are the habits that keep weight off for years, not weeks.
The magpie effect: stop chasing shiny things
Humans are magpies. We love shiny, new things - especially when they promise fast results. But in nutrition, shiny rarely equals effective. Keto, juice cleanses and detox teas all sparkle with novelty. Yet the principles of healthy eating haven’t changed: balance, variety, moderation.
So next time you see a diet promising miracles, pause. Ask yourself: Can I do this for the next six months? The next year? The rest of my life? If the answer is no, it’s not a solution, but a distraction.
The real magic lies in the boring advice we've heard for decades: eat less, move more, watch portions, and be patient
Here's a better way to start the year
If you’re itching for a fresh start, skip the crash diet. Instead, pick one or two small, sustainable changes. Swap sugary drinks for water. Add a daily walk. Cook one extra meal at home each week. These changes might feel slow, but they compound over time. Unlike aggressive diets, they don’t come with a side of burnout.
Aggressive, short-term diets might deliver quick wins, but they rarely deliver lasting success. They’re seductive, yes - but they’re also unsustainable. The real magic lies in the boring advice we’ve heard for decades: eat less, move more, watch portions, and be patient. It’s not glamorous, but it works - because it’s grounded in evidence, not hype.
So, this year, resist the shiny shortcuts. Build habits, not houses of cards. Your future self will thank you.
Follow RTÉ Brainstorm on WhatsApp and Instagram for more stories and updates
The views expressed here are those of the author and do not represent or reflect the views of RTÉ
