In the last few years, there\u2019s been a lot of interest in calorie-restricted diets for weight loss.<\/p>\n\n\n\n
These can vary significantly, from intermittent fasting (where you restrict eating to a certain window of the day), alternate day fasting (where you consume limited or no calories on every other day) to the Fast 800 which promotes rapid weight loss by drastically reducing calories with the \u201cMediterranean diet\u201d.<\/p>\n\n\n\n
The basic idea might seem obvious: reduce how much you eat, and you\u2019ll theoretically lose weight.<\/p>\n\n\n\n
But are they healthy? And will you just put the weight back on if you stop?<\/p>\n\n\n\n
The amount of energy you need each day varies based on your age, sex, body composition, how physically active you are, and any background health considerations.<\/p>\n\n\n\n
Calorie-restricted diets aim to reduce a person\u2019s overall energy (calorie) intake. And in certain instances, when managed carefully by health-care teams, there is evidence for their benefits beyond weight loss, including as an intervention before surgery.<\/p>\n\n\n\n
The general aim is to eat less than the body uses, causing the body to draw on its stored energy \u2013 fat. Over time, this imbalance, generally using more energy than you eat, can lead to weight loss.<\/p>\n\n\n\n
But these diets are not meant to be followed forever. Most involve a period of restricting calories, before transitioning to less restricted diet that helps you maintain a healthy weight long-term.<\/p>\n\n\n\n
For example, some diets recommend a moderate restriction: eating 500\u2013600 fewer calories a day. This is like subtracting one take-away hamburger from your normal daily intake.<\/p>\n\n\n\n
Very low calorie diets (also called very low energy diets) typically recommend eating less than 800 calories across the entire day.<\/p>\n\n\n\n
These are medically recommended diets \u2013 for example, where short-term rapid weight loss before surgery could reduce someone\u2019s risk of complications.<\/p>\n\n\n\n
They require very close monitoring and support from a dietitian, to make sure they still get enough essential minerals and vitamins and don\u2019t get malnourished.<\/p>\n\n\n\n
The short answer is yes \u2013 at first.<\/p>\n\n\n\n
Research consistently shows calorie-restricted diets can significantly reduce weight and waist circumference.<\/p>\n\n\n\n
They can also improve the way the body manages its blood sugar levels and cholesterol levels helping to reduce cardiovascular risk, particularly among people who are above a healthy weight or live with obesity or type 2 diabetes.<\/p>\n\n\n\n
But a lot of the evidence for calorie-restricted diets comes from short-term studies of only 2\u201312 weeks.<\/p>\n\n\n\n
Unfortunately, maintaining the weight change is much more challenging than achieving it in the first place. Many people regain some or most of the weight they initially lost, once the diet ends.<\/p>\n\n\n\n
Highly processed foods are cheap, convenient and everywhere around us. This makes long-term restrictive eating patterns very difficult to follow.<\/p>\n\n\n\n
But there\u2019s more to it.<\/p>\n\n\n\n
Losing weight also triggers a range of adaptations as our body tries to restore it.<\/p>\n\n\n\n
Basically, your body tries to defend against more weight loss. For example, as you lose weight, the hormones that regulate appetite change \u2013 often making you more hungry.<\/p>\n\n\n\n
Meanwhile, you may also feel less full, and as your body becomes more energy efficient, it will burn fewer calories than before.<\/p>\n\n\n\n
This doesn\u2019t mean the body enters \u201cstarvation mode\u201d as is often claimed on social media. But your weight loss slows over time, and hitting a plateau is very common. This can trigger some people to regain weight as motivation falters.<\/p>\n\n\n\n
For many people, the feeling of constant hunger is the main reason they don\u2019t continue with calorie-restricted diets.<\/p>\n\n\n\n
Feeling hungry all the time can impact your mood, sleep and your relationship with food. It can also be your body telling you something else is going on.<\/p>\n\n\n\n
Constant hunger can indicate you\u2019re stressed or have an underlying health condition.<\/p>\n\n\n\n
So you should speak to your doctor if you feel like your appetite has increased or decreased for no reason, and especially if you also feel dizzy, very tired and also have difficulty concentrating.<\/p>\n\n\n\n
If you have these symptoms, it\u2019s likely your doctor will advise you to stop a calorie-restricted diet.<\/p>\n\n\n\n
Calorie-restricted diets may be suitable for people above a healthy weight or with obesity, who wish to lose weight. For some chronic conditions, such as type 2 diabetes or arthritis, losing weight can also help manage the disease.<\/p>\n\n\n\n
But they\u2019re not recommended for:<\/p>\n\n\n\n
For most people, dietitians would recommend people focus on improving their overall diet and creating long-term habits, rather than simply cutting calories as aggressively as possible.<\/p>\n\n\n\n