For people who’ve tried a low-calorie diet in the past, the thought of cutting calories each day probably brings back bad memories.
Most diets involve reducing calories in some way or another: Some introduce foods that fill you up faster but contain fewer calories, such as fruits and vegetables in place of processed foods. Other diets restrict your options, and eating the same food sources becomes repetitive and less interesting, so you consume fewer items.
Still other diets combine both strategies, such as diets recommending a low-calorie food such as a tomato, or a special shake that you make, for most or all of your meals.
But new research shows that low-calorie diets can help with surprisingly more than your weight.
What Is a Low-Calorie Diet?
A low-calorie diet is one that restricts your intake to 1,200 to 1,600 calories per day for men, and 1,000 to 1,200 calories per day for women. Some people go on a very low-calorie diet for rapid weight loss, often consuming only 800 calories a day. This type of diet usually includes special foods such as shakes, bars, or soups to replace meals and for added vitamins. Very low-calorie diets can help a person achieve weight loss of up to 3 to 5 pounds per week.
For weight loss, most people should consider a low-calorie diet rather than a very low-calorie diet. Less extreme diets are easier to follow, they interrupt normal daily activities less, and are less risky if you’re over 50 or have other health problems. In addition,gallstones have been reported in people who go on very low-calorie diets.
Keep in mind that most diets only work when you make healthy lifestyle choices at the same time, including increasing daily exercise and reducing your sedentary time throughout the day.
Good Reasons to Try a Low-Calorie Diet
The obvious reason to restrict calories is to help with weight loss. Why else give up something that you enjoy? Yet very interesting data from animal studies throughout the animal kingdom shows additional effects of calorie reduction. As reviewed in Molecular Aspects of Medicine in June 2011, studies show that animals subjected to periods of calorie restriction, including primates, have:
- Longer lives
- Higher levels of physical activity
- Lower rates of cancer
- Less age-related degeneration of the brain
- Improved reproductive performance
Some of these findings may seem odd to anyone who’s tried to fast or restrict their calories and then felt the early fatigue, weakness, lack of energy, nausea, and stomach pains associated with their efforts.
Keep in mind that the animal studies and observations involved regular periods of calorie restriction followed by, or within the context of, a healthy diet. In other words, the animals’ bodies had time to adapt in a healthy manner to slightly less caloric intake over a long period of time.
What Happens When People Restrict Calories?
When I talk with patients about cutting calories for heart health, I don’t think I’ve had anybody tell me they want to do it to live longer, feel better, and have a better quality of life. But this is because most people think of exactly how they’re going to feel the first few days or weeks after they start, rather than taking a long-term outlook.
A study published in June 2016 in JAMA Internal Medicine provided unique insight into what happens to people when they restrict their calories. This study included people who were not obese specifically because weight loss in obese people is often used to lower risk of diabetes, high blood pressure, sleep apnea, and coronary artery disease in addition to improving their quality of life.
The investigators in this study followed 218 participants for two years. The average age was 38, and 70 percent were women. At the time of enrollment, they could have a body mass index (BMI) up to 28, but no lower than 22. The groups were randomized to either continue with their normal diet or participate in a calorie-restricted diet. The diet contained approximately 25 percent fewer calories than they had previously eaten.
Why did the researchers choose a 25 percent reduction in calories? They thought this level was the most that could be reduced and sustained for the entire two-year study. Participants met in groups and had web-based resources to assist with their diet. Registered dietitians monitored participants’ weekly food diaries to determine total calories. All participants were encouraged to exercise at least five days a week for 30 minutes at a time.
The authors reported several important findings. First, and not too surprisingly, the people in the group who ate fewer calories lost more weight. On average, people in this group lost 7.6 kg (16.7 lbs) compared to those in the other group, who lost 0.4 kg (0.9 lbs).
What was even more interesting was the impact of calorie restriction on quality of life. Those who restricted calories reported better moods and less daily tension, and they rated their overall health better throughout the study period.
The calorie-restricted group also reported improved sleep duration and quality. Finally, the calorie-restricted group experienced more sexual drive and arousal, and better sexual relationships, than the other group.
Is a Low-Calorie Diet Right for You?
If you’re overweight or obese, the choice may be simple. Weight loss is a critical lifestyle choice to improve your general health and lower your risk of cardiovascular disease, diabetes, sleep apnea, premature joint disease, high blood pressure, and cancer.
But lowering your risk for these diseases is only part of the potential benefit of cutting calories. Many other benefits of calorie restriction can improve your qualify of life and daily functioning. If you’re in the normal weight range, this new study also suggests a potential benefit of calorie restriction if done carefully — as long as your BMI doesn’t drop below 22.
If you chose to cut your calories, consider the expertise of the study investigators in this trial and aim for a 25 percent reduction. This is the level at which there was some benefit and that was at the same time tolerable, so it’s possible to keep it up. Here’s how to get started:
- Keep an accurate diary of your food intake for one to two weeks.
- Use an online calorie counter to help you determine your daily calorie intake.
- Plan to restrict your calorie intake by 25 percent over the next month.
- Write out a menu each week that includes a wide variety of foods that you enjoy.
One of the easiest ways to cut calories is to increase your intake of whole fruits and vegetables, which you’ll find are more filling and less calorie dense. Also consider making these diet changes with other people, who can provide social support and accountability — powerful ways to improve the likelihood that you’ll succeed.
As you begin to experience the improved quality of life, sleep, and other benefits, these will help positively reinforce your goals and make the calorie-restricted diet a daily habit. And as you feel better, become more active, and maintain a healthy diet, you’ll have the added benefit of having to see your local cardiologist less.