If you’re on a weight loss journey, you may be wondering how to predict how long it will take you to reach your goal. Generally speaking, there is no way to accurately predict how long it will take to lose weight. How long it takes to lose weight depends on your weight loss goal.
Here are some insights into how weight loss works and why predicting how fast it takes can be tricky.
Losing One to Two Pounds per Week Is Recommended
The Centers for Disease Control and Prevention (CDC) says that people who lose weight gradually and steadily (about one to two pounds per week) are more likely to keep the weight off.
Your rate of weight loss may also predict the type of weight you lose. Rapid weight loss is defined as losing more than two pounds per week for several weeks. Compared to rapid weight loss, gradual weight loss has been shown to result in the loss of more pounds of total fat and a lower body fat percentage, the body’s ratio of fat weight to lean weight.
And while many people would like to lose weight faster, even modest weight loss has been shown to result in health benefits, which include improvements in blood pressure, blood cholesterol, and blood sugar.
You May Lose Weight Faster if Your Starting Weight Is Higher
Losing one to two pounds per week is a rate that's reasonable for many—it shouldn't require extreme eating or exercise habits. That said, you may lose weight faster if you have more weight to lose, simply because changing your diet may result in a larger calorie deficit.
For example, according to the Body Weight Planner from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), a 40-year-old woman who is 5’4” and 200 pounds with a light activity level would need to eat 2,190 calories per day to maintain her weight. In contrast, a woman of the same age, height, and activity level who weighs 150 pounds would need to eat 1,873 calories to maintain her weight. If they both began eating 1,500 calories per day, the 200-pound woman will have a larger daily calorie loss.
A 2021 study concluded that while there is no single best strategy for weight management, an energy or calorie deficit is the most important factor in weight loss.
But as you lose weight, the deficit shrinks, which is why the rate of weight loss tapers the closer you get to your weight goal, regardless of where you started.
“Those last 10 pounds are going to be much more stubborn than the 50 pounds that may seem to melt off,” said Jamie Johnson, RDN, a member of Health’s Medical Advisory Board. “To lose those 10 pounds, try decreasing your calorie intake or increase your exercise time or intensity.”
Changing the Type of Calories You Eat May Speed Weight Loss
While calories matter, the quality, balance, and timing of the calories you take in also play key roles in how weight is lost.
Simply slashing your caloric intake while still consuming a lot of processed foods, or eating a big chunk of your calories in the evening, may not result in losing weight as quickly. The following three research reports help to illustrate these facts.
- A 2017 study found that replacing refined grains with whole grains for six weeks resulted in higher resting metabolic rates (greater calorie burning), among both men and postmenopausal women.
- Another study found that in postmenopausal people, those who ate the recommended amount of protein experienced the greatest benefits in metabolism and insulin sensitivity (how well insulin works to regulate blood sugar), even compared to those who followed a high-protein diet.
- And a 2020 study, found that eating a late dinner worsened blood sugar tolerance and reduced the amount of fat burned.
Eating Too Few Calories Can Stall Weight Loss
If you're tempted to eat as few calories as possible, please talk with your personal healthcare provider.
In one 2021 study 108 adults with overweight or obesity were randomly assigned to very low calorie diets (VLCDs) that provided 600-700 daily calories with different protein levels (52 grams or 77 grams per day) for eight weeks. While both VLCDs decreased body weight and fat mass, researchers found that the higher protein diet did not prevent the loss of lean mass, like muscle, or a decrease in resting metabolic rate, the number of calories burned at rest.
The National Health Service (NHS), which provides publicly funded health care in the UK, also states that VLCDs are likely to be less nutritionally complete, aren’t suitable for most people, and may result in side effects that include hunger, low energy, headaches, dizziness, cramps, and hair thinning.
“It may sound counterintuitive, but too few calories can actually hinder your weight loss efforts,” said Johnson. “When your body doesn’t get enough energy to fuel itself, it kicks into starvation mode and starts to hold onto every calorie.”
Genetics and Other Factors May Affect Your Weight Loss Rate
Metabolism, which is basically how your body burns calories, is an important factor in the weight loss puzzle, and it's complex. Appetite-regulating hormones also play a role in weight loss. Both can be affected by factors like poor sleep, stress, and the makeup of your gut microbiome, the collection of microbes that reside in your digestive system.
Research shows that gut microbiota can actually influence both sides of the calorie balance equation. It impacts how we utilize calories from the foods we eat, and how we burn or store them.
For this reason, weight loss—and how quickly you may drop pounds—isn't so straightforward.
Weight Fluctuations Are Normal
It's also important to know that weight loss isn't always linear. It's normal for your weight to shift from day to day, even hour to hour. When you step on a scale, you're measuring everything that has weight:
- Your muscle
- Body fat
- Water volume, which can change quickly and wildly
- Undigested food, even if it will all later be burned off
- Waste in your GI tract that your body hasn't eliminated yet.
If you're retaining water, due to PMS, an extra salty meal, medications, or other reasons then your weight on the scale will be higher, even if you've simultaneously lost body fat.
“Very rarely is weight loss linear, so do not get discouraged if you see your weight go up a few pounds,” said Johnson. If you are strength training, (which is recommended, since muscle helps burn more calories) you might see the scale go up if you’re gaining muscle mass. “Don’t be so caught up in the number on the scale, but instead gauge how you feel in your clothes,” she added.
Pursuing weight loss might not always be an easy decision, but it doesn't mean that getting started has to be. You can use the following steps from the CDC to begin:
- Make a commitment to yourself to lose weight
- Determine your starting points with height, weight, risk factors, diet, and lifestyle
- Set specific, realistic goals that leave room for forgiveness
- Find ways to educate and support yourself
- Monitor and reward your progress over time
“Everyone wants a quick fix, but unfortunately when it comes to weight loss, slow and steady wins the race,” Johnson said. Quick fixes are usually the result of fad diets that aren’t sustainable in the long run. “The best approach to weight loss is a method that builds long-term healthy habits as part of your lifestyle and doesn’t require drastic measures that leave you starving or negatively impact your health,” she added.
Weight loss is complex, and nobody can realistically forecast exactly how much weight you'll lose within a given time frame. The truth is that focusing on healthy, balanced habits you can stick with is far more important.
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