There’s no shortage of dramatic weight loss transformations on Instagram, which makes losing 2.5kg week seem pretty easy. But losing that kind of weight in just seven days can be unhealthy, and even impossible, for some people.
Every dieter wants to know the amount of weight they can lose in a week, but there is no safe limit according to Dr. Konstantinos Spaniolas, associate director of the Bariatric and Metabolic Weight Loss Center at Stony Brook University. This is because a variety of factors impact how quickly pounds are shed, including starting weight.
Spaniolas says that losing one per cent of your body weight per week is considered rapid, but within reason. However, fast results come with a price: namely muscle loss, which no one wants. This is why experts recommend a long-term plan that’s easy to sustain.
Dr. Yoni Freedhoff, M.D., author of Why Diets Fail and How to Make Yours Work, agrees there are other downsides to losing weight quickly, like nutritional deficiencies, loose skin and gallstones.
Looking to drop body fat and retain your muscle mass? Consider these 7 tips when planning your weight loss routine:
Your starting point
The more excess weight you have to lose, the larger the percentage of lost weight will come from fat, says Kevin Hall, Ph.D., a researcher at the National Institute of Diabetes and Digestive and Kidney Diseases. Say you start at 136kg—a goal of one per cent fat loss per week means you’ll shed 1.3kg in a week, Perry says. But if you’re just looking to drop 4.5kg from a relatively lean frame, you’ll probably have a harder time retaining muscle mass.
You’ve heard us say it before: Resistance training is key to keeping muscle while burning fat. In one Columbia University study, participants cut calories and were assigned either to strength-train or do cardio three times a week. After eight weeks, everyone lost more than 9 per cent of their body weight. But in the aerobic group, 20 per cent of that came from lean tissue (mostly muscle), while the resistance group limited lean-tissue loss to 8 per cent.
Your protein intake
Protein provides essential amino acids that your body uses to make muscle. Skimp and you’ll lose more muscle. Spaniolas recommends eating about .8 to 1 gram of protein for every pound you weigh in order to retain muscle.
Your sleep habits
Not getting enough shut-eye throws hunger and metabolism hormones like leptin and ghrelin out of whack, Perry says. In a small study published last year in Annals of Internal Medicine, volunteers on a reduced-calorie diet slept either 5.5 or 8.5 hours a night. In two weeks, they both lost a little more than 2.9kg—but those who slept more lost twice as much of that from fat.
How much you’ve already lost
The smaller you are, the fewer calories you’ll burn, Freedhoff says. But there are even more complex hormonal and metabolic shifts at work, making it harder to burn fat the longer you’re losing. Scientists are still working to understand the mechanisms, but research has shown that people who have lost weight burn fewer calories than people who never dieted.
Choose a diet that works for you
“Not every plan fits every patient,” Spaniolas says. If you prefer to eat high-fat foods, then the trendy keto diet may work for you. However, this doesn’t mean carb lovers need to forego pasta to see results.
Reduce calories slowly
Spaniolas says correctly estimating how many calories your body needs is complicated, but recommends using a chart or calculator from the National Institute of Health. From there, you can omit about 500 calories per day to lose weight, but shouldn’t go much lower to begin with. And even then, he says it may not be easy to sustain this reduction in calories if your already lean and need fewer calories to begin with.