If you’re looking to lose weight, it makes sense to do some research to see what diets are the most popular right now. But while there are plenty of trending eating plans out there, there’s one old standard that’s suddenly becoming popular again: the calorie-deficit diet.
The diet is a huge time saving option and simple at first: it doesn’t tell you which foods you can and can’t eat. Instead, it focuses solely on calories, which is the amount of energy released when your body breaks down food. The more calories a food has, the more energy it can provide your body.
Your body needs some calories to function normally, but if you eat more calories than you need, the excess will be stored in your body as fat.
This is where a calorie deficit diet comes in. But how does a calorie deficit diet work and how do you know if it’s right for you?
So what is a calorie deficit diet?
The concept behind a calorie deficit diet is quite simple: you try to eat fewer calories than you burn. “A calorie deficit is when we expend fewer calories than our bodies burn in a day, both in terms of our natural resting energy expenditure — your natural metabolism — and any exercise or physical activity we do in addition to that.
Can a Calorie Deficit Diet Help You Lose Weight?
If you calculate correctly, a calorie deficit diet will help you lose weight. Calories are one of the main factors in gaining or losing weight. If a person consumes fewer calories than they burn, it can lead to weight loss.
So if you normally eat 2,200 calories a day, you should lose weight on a calorie-deficit diet if your goal is to reduce it to around 2,000 calories a day.
There’s a reason for that. If we consume fewer calories than we burn, our bodies have to get energy from somewhere to continue their natural functions. The extra energy to maintain bodily functions comes from the energy stored in our own bodies. Normally, your body burns fat first, followed by glycogen, which is a carbohydrate that your body converts into after you eat it. And when that fat is burned, you end up losing weight.
How to go on a calorie deficit diet?
There are several possibilities for this. The gold standard is knowing how many calories you burn in a day. This may involve a test known as indirect calorimetry, which measures the amount of carbon dioxide you exhale, combined with some complicated calculations to find out how much energy you burn at rest (i.e. just sitting and doing nothing). There’s also something called the Bod Pod that can measure how much energy you burn while resting, but neither method is available to everyone.
So you can use an online equation like weight planners to figure out what your daily calorie intake is to reach a certain weight goal. To use it, enter basic info such as your height, current weight, age, and activity level, then enter your goal weight and how long it will take you to reach it. From there, the planner gives you an estimate of how many calories you need to eat to reach your target weight in the time you set, and how you can keep it off.
But it’s not an exact science and doesn’t take into account things like how much muscle mass you have (muscle tissue burns more calories than fat) and your individual metabolism. There are so many factors that affect energy consumption. It can still give you a rough estimate to work with.
If you want to rest and you know you want to lose about a pound a week, you can try cutting 500 calories from your existing diet. One pound is roughly equivalent to a deficit of 500 calories per day for a week.
But the ability to cut a lot of calories and feel comfortable doing so depends on what you’ve eaten beforehand. If you have lots of high-calorie processed foods and sweets in your diet, replacing them with lots of fruit and vegetables, lean protein, and healthy fats may not feel like a big deal when it comes to your hunger, she says. However, if you’re already eating healthy enough to begin with, you may find it more comfortable cutting 125-250 calories a day instead, knowing that it may take you a little longer to lose weight.
How Much Calorie Deficit is Too Much?
Adult women consume between 1,600 and 2,400 calories per day, while men should aim for between 2,000 and 3,200 calories per day. (The lower limit is when you do little or no activity each day.) Anything below the minimum is not considered healthy, so be aware that you may have an overly large calorie deficit.
You may also run into an overly large calorie deficit if the weight you’re losing “gains too fast, like five pounds a week or more,” Symptoms such as fatigue, nausea, dizziness, and constipation can also be signs that you’re losing weight too quickly.
In general it is highly recommend cutting out no more than 15 to 20 percent of calories.
If you’re interested in trying a low-calorie diet and aren’t sure where to start, consult your GP or a registered dietitian – they should be able to provide you with personalised guidance.