From counting calories or restricting carbs, to eating only during certain time periods of the day, there are a plethora of diets that people try in order to lose weight.
In fact, a 2019 study from Kantar found that, at any given time, 45% of UK women are actively trying to lose weight, as are 30% of British men.
A separate study from The Laughing Cow found that the average Brit will start and fail 189 diets in their lifetime and attempt three diets each year. So why do most diets not work?
“Most people fail to stick with their diet long enough for it to work sustainably,” nutrition expert Vidur Saini from Fitness Volt explains.
“They are strong out of the gate but soon fall off the wagon and return to their previously sub-optimal eating plan.”
Saini adds that this is why so many of us regain the weight we lose from dieting. “It seems long-term, sustainable weight loss is rare nowadays."
Why do most diets fail?
1. You ban entire food groups
Some diets, such as the paleo diet, bans all processed foods, while the keto diet bans carbohydrates, for example. Saini explains that the problem with cutting out certain food groups is that it is “guaranteed to trigger cravings”.
“Essentially, any diet that bans a particular food or food group will invariably result in cravings, driving you to cheat on your diet,” he adds.
“Allow yourself the smallest amount of this particular food or drink to allow your body to feel like it isn’t being deprived of something. Everything in moderation.”
2. Ingredients cost too much
As the cost-of-living crisis continues, buying fresh ingredients needed for some diet plans isn’t always financially viable for many households.
“For example, some diets specify that you must eat expensive foods and that somehow these products are better for weight loss than those that are more reasonably priced,” Saini observes.
“Organic vegetables and grass-fed beef from free-roaming cattle cost a lot more than the basics you get at [supermarkets] but nutritionally are not all that different. They certainly won’t help you lose weight faster.
“For a diet to be sustainable, you need to be comfortable with how much your food costs. For example, if your grocery bill doubles overnight, you have got a ready-made excuse for quitting your new eating plan.”
3. Your diet is too complicated
“To make diets unique, they are often unnecessarily complicated. This complexity can often cause people to make mistakes or just give up after a while,” Saini explains.
Ultimately, he adds, for a diet to work it needs to be simple enough to be carried out long term.
4. Your diet must be perfect or you see it as a failure
Because diets can be very restrictive and allow little to no room for variation, this often leads dieters to go off course. When this happens, they feel as if they have “failed” their diet and return to their old eating habits.
“The reality is that your diet doesn’t have to be perfect,” Saini says.”It just needs to be pretty good most of the time, which is more than enough to reach weight-loss goals.”
5. The diet isn’t made for long-term success
Any diet that puts a time frame on weight loss – such as those that claim you can lose a certain amount of weight in 30 days – is not built for success.
“Excess body fat accumulates over many years, and no one goes to bed lean and then wakes up fat,” Saini explains.
Achieving your body goal could take many months, or even years, adds Saini.
"To achieve a significant result in just a few weeks, any diet must be very restrictive and, therefore, it’ll be unsustainable as your body will soon put the weight back on.
“Before considering any diet, ask yourself, ‘can I follow it for the next six to 12 months?’”
6. The diet is based on little to no science
“Some diets are based on very flawed science or may not be based on any science at all,” Saini says.
“One example of this is calorie-burning or negative-calorie foods, such as celery. No food burns more calories than it contains, and these claims are very misleading.”
Instead, Saini explains that effective diets work by “manipulating your calorie balance”. “Consume fewer calories, and your body will make up the shortfall by using stored body fat for energy. No deficit means no fat burning. There are no shortcuts around this law of thermodynamics.
“As a rule, if a diet promises something that sounds too good to be true, it probably is, so don’t fall for it.”
The best way to lose weight, and ensure your diet doesn't fail
“Healthy eating doesn’t have to be complicated or unpleasant, and weight management doesn’t have to take over your life,” Saini explains.
“You don’t even have to give up your favourite foods. However, you will need to quit looking for short-term fixes and adopt healthier long-term habits.”
He recommends calorie counting as the best way to achieve long-term weight loss.
“Consume fewer calories than you need, and you will burn fat and lose weight, but consume more than you need, and you will gain weight,” he explains.
A study released by Johns Hopkins University in the US earlier this year confirmed that calorie counting and limiting portion sizes were the best way to lose weight.
Other expert-approved tips for weight loss include not limiting which food groups you eat, adding more fibre to your diet, drinking more water, and doing exercise you enjoy.
Watch: 95% of Americans have tried to lose weight within the last 5 years