- Calorie-deficit diets slowly and temporarily limit the number of calories you consume each day.
- When in a calorie deficit, your body burns more calories than it takes in, which may promote weight loss.
- It's important to eat a well-rounded diet while in a deficit to avoid malnutrition or nutrient deficiency.
Almost any weight-loss diet requires a sacrifice, like swearing off your favorite foods or drinks. It's no wonder people don't stick with them and typically regain weight.
It doesn't help that the science is conflicting, too. The evidence behind "calories in, calories out" is strong but research continues to prove that restrictive meal plans — like low-carb or low-fat — are ineffective and unsustainable long term. So what is a health-conscious person to do?
Enter: the calorie-deficit diet.
Unlike meal plans that urge you to eliminate anything short of baby carrots, the calorie-deficit diet provides a clear path to weight loss without saying Sonora to your beloved treats. In essence, by eating fewer calories than your body burns each day, your body will then store less overall fat. Over time, this may lead to weight loss.
Now let's get one thing crystal clear: calorie deficit diets are not meant to go on forever and are still partially restrictive.
They're designed to slowly and temporarily limit the number of calories you eat until you hit your desired, healthy weight. You'll then slowly add more calories to your diet to help maintain the weight you've lost.
And all of this should be done without malnutrition or depriving your body of necessary nutrients — and under the supervision of a doctor and/or a dietitian.
Though that sounds good on paper, I spoke to two dietitians for insight into the benefits of a calorie-deficit diet, its drawbacks, and who should try it.
What is a calorie-deficit diet?
Calorie counting has been used by health and fitness professionals for years to help people manage their weight. Registered dietitian and head of nutrition and wellness at Kilo Health, Kristina Zalnieraite, says that creating a calorie deficit (or CD) is done by limiting food and increasing movement.
"Your body burns calories through a combination of your basal metabolic rate (BMR) and physical activity," Zalnieraite says. "BMR defines how many calories your body burns at rest to maintain basic functions like breathing and keeping your heart beating. To create a calorie deficit, your body turns to stored energy [fat] to make up for the energy it needs but isn't getting from food. Over time, this can lead to weight loss."
So, how many calories do you need to cut to create a deficit that moves the scale? It varies, but the National Library of Medicine says a good rule of thumb for people who are overweight (meaning they have a BMI over 25.0) is 500 calories per day. However, 500 calories may be too many for someone who has less weight to lose.
Using a calorie deficit calculator — like this one from the National Academy of Sports Medicine — can help you hone in on a realistic goal. Just be wary of cutting too much, as a very low-calorie diet (800 calories or fewer) can cause nutritional deficiencies and concerns for malnutrition.
Aiming for a steady weight loss of 1 to 2 pounds per week is considered a healthy rate whereas losing any more can increase your risk of health problems like gallstones.
While it sounds — and is — relatively simple, Zalnieraite notes that creating a calorie deficit is just one part of a comprehensive weight loss plan. She says it should be paired with eating nutrient-dense foods, staying hydrated, getting enough sleep and exercise, and setting realistic goals.
Since calorie needs vary based on factors like physical activity level, age, sex, weight, and height, it's crucial to use a personalized approach to make sure you're losing weight in a slow and sustainable manner.
Even though there currently are studies looking into long-term calorie restriction as a method of disease prevention and longevity, most experts only recommend eating in a CD temporarily until you reach your healthy goal weight. Then you need to slowly start adding calories back in until you reach the average needs of your demographic.
Here's the recommended amount of calories folks should eat each day, depending on their age:
|
Age Range |
Men |
Women |
|
Teen |
3,000 |
2,500 |
|
Average Adult |
2,400 |
1,800 |
|
Active Adult |
2,800 |
2,200 |
|
Older Adult |
2,000 |
1,600 |
Sources: NHS and Cleveland Clinic
What are the benefits of a calorie-deficit diet?
Even though most people may turn to calorie-deficit eating to lose or manage their weight, Zalnieraite says there are several other scientifically proven benefits.
"Studies show that even moderate calorie restriction reduces total body fat and other health risks," Zalnieraite says. "Calorie restriction without malnutrition may reduce the risk of developing type 2 diabetes, heart disease, cancer, and neurological disorders in humans."
Here are a few more benefits of doing a calorie-deficit diet:
- Improved insulin sensitivity: Eating in a calorie deficit has been shown to improve insulin sensitivity, reducing the risk of developing diabetes and other metabolic disorders. However, a diet heavy in heavily processed foods, refined carbohydrates, and saturated fats can stimulate insulin production, making it harder to lose weight.
- Possible increased longevity: Recent animal studies found calorie restriction can increase lifespan by 10%. More research is needed to confirm the same in humans.
- Reduced inflammation: CD eating has been shown to reduce inflammation in the body, which lowers the risk of chronic diseases such as heart disease and cancer when eating a nutrient-dense diet.
- Improved cardiovascular health: Eating less helps lower blood pressure and may minimize the risk of developing heart disease.
What are its drawbacks?
Although eating in a calorie deficit can be an effective way to lose weight, it's not without its drawbacks — especially when it's done without the guidance of a healthcare professional.
Registered dietitian, Katherine Gomez, says that restricting your calories too much can reduce fertility, weaken your bones, and even lower your immunity.
"Calorie-restricted diets may not provide sufficient amounts of iron, folate, or vitamin B12," she says. "This can lead to anemia and extreme fatigue."
Zalnieraite says other potential consequences include:
- Slower metabolism: Restricting calorie intake for prolonged periods may slow the metabolism, making it harder to maintain weight loss results over time.
- Loss of muscle mass: Eating too few calories can lead to muscle mass loss, negatively impacting overall strength and physical function.
- Hunger and cravings: Consuming fewer calories can lead to feelings of hunger and cravings, making it challenging to stick to a calorie-restrictive diet or lead to binging on foods due to increased hunger.
- Risk of disordered eating: Restrictive eating patterns, especially without proper guidance, can increase the risk of disordered eating and eating disorders.
Since all calorie-deficit diets should be temporary, many people are concerned about regaining the weight they lost once it's time to resume regular eating.
However, new studies show that gradually increasing your calories — in the same steady manner as you reduced them — can help limit any potential weight gain and keep the extra pounds off long-term. Increasing protein, fiber, and physical activity are all great strategies to combat eating excess calories or upping your calorie intake too quickly.
Because of the numerous potential risks associated with calorie restriction, it's important to speak with your healthcare provider before starting a new diet. They can help you create an effective plan that fits your individual needs and health goals, as well as monitor your progress to ensure you're managing your weight safely and healthily.
Can anyone do a calorie-deficit diet?
While its simplicity makes the calorie-deficit diet appealing, Gomez says not everyone should follow it.
"Low-calorie diets are for adults who are obese and severely obese — defined as having a BMI over 30 and 40," she says, adding that it's not for anyone under 18, pregnant women, breastfeeding women, or people with a history of disordered eating. "They're not a complete solution for weight loss, and you still must develop healthy habits."
Zalnieraite adds that "setting goals that are too aggressive and creating a very low-calorie deficit may lead to a lack of energy, lack of nutrients, or even put a person at risk of disordered eating."
There is also no singular strategy for going on a calorie deficit diet. Studies show that all weight loss strategies should be individualized, so if you're interested in exploring this weight loss route, work with your doctor to devise a calorie-cutting plan that addresses your specific needs.
That leaves us with just one question: are calorie-deficit diets the best and healthiest way to lose weight? Again, no singular diet can be prescribed to everyone. However, research shows that "conventional hypocaloric diets are safe, healthy, and modestly effective."
No matter what diet you're following, Gomez says it's more about the kind of food you're eating rather than how many calories.
"A low-calorie diet is wrongly promoted," Gomez says. "It works for a short time, but if you do not have time to reduce weight properly, it can leave you with a lack of nutrition. Choosing the right food helps you lose weight and maintain weight."
Insider's takeaway
A calorie-deficit diet may be able to help you effectively manage your weight, but it's not a one-size-fits-all or long-term solution.
Before starting any restrictive eating plan, make sure to consult with your healthcare provider first, who can help you create a plan that fits your individual needs and goals while minimizing the risks associated with extreme calorie restriction.
After all, cutting calories only works if it's done in a slow and controlled manner, that you're still getting proper daily nutrients, and with the goal of improving your overall health rather than as a quick fix to reach extreme weight-loss goals.