Why Losing Weight Fast Isn’t a Good Idea, and What to Do Instead

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Everyone wants to know the fastest way to lose weight. And with so many diets promising just that, it's no surprise the trend continues.

Anything that sounds too good to be true most likely is. Rapid weight loss fad diets are usually gimmicks and are largely unsafe. Plus, losing weight too fast has some significant downsides.

The key to losing weight and keeping it off is approaching it in a sustainable, thoughtful, and balanced way.

If weight loss is your goal, consulting with a health care professional, like a registered dietitian, can help you develop an individualized plan that's sustainable, realistic, and compatible with your lifestyle.

What is Considered Fast Weight Loss?

Rapid weight loss is at least a 5 percent reduction in body fat within five weeks. This equates to approximately two or more pounds per week, depending on an individual's body weight.

Healthy Rate of Weight Loss

Slow and steady, or "healthy," weight loss is 0.5 to 2 pounds per week and an ultimate goal of 5-10% of total body weight within the first six months.

But if healthcare professionals recommend weight loss of one to two pounds per week, why is more than that dangerous? Studies find that both slow and rapid weight loss are effective in reducing body weight, but the faster you lose weight, the more lean mass you'll burn and the more likely you will gain it back over time.

Why is Rapid Weight Loss Dangerous?

There are many evidence-based reasons supporting the dangers of rapid weight loss, including loss of lean muscle mass, disordered eating habits, unsafe use of supplements, and more.

It Doesn't Preserve Lean Muscle

Weight loss and fat loss are not the same. You can lose weight without losing body fat. If this happens, you lose lean body mass, such as muscle, organ tissues, or water weight. Losing lean mass has several negative health consequences, including fatigue, increased risk of injury, low energy, reduced metabolism, and a decline in neuromuscular function.

One study comparing the effects of rapid weight loss and slow weight loss on body composition found that both diets resulted in weight loss and improvements in blood sugar and cholesterol levels. However, the slow weight loss group saw greater improvements in body composition. That means losing weight slowly helps preserve muscle while losing weight quickly does not.

When losing weight, it's important to focus on preserving lean mass (muscle) so that you end up losing primarily body fat and shift your body composition.

It Promotes Disordered Eating Behaviors

Crash diets and diets that result in rapid weight loss tend to be more restrictive in nature and can promote unhealthy eating behaviors. Plus, studies show that the more extreme a diet is, the more likely you will stop it prematurely.

Though little is known about the harmful effects of dieting, some studies show that restrictive diets like those that promote rapid weight loss are linked to negative psychological effects, including disordered eating behaviors and orthorexia.

The best way to prevent disordered eating behaviors is to maintain a healthy relationship with food and avoid restrictive diets. This is quite the opposite of any diet that results in rapid weight loss.

It Includes Potential Use of Unsafe Supplements, Products, or Medications

The measures people take to reach their weight loss goals quickly are often risky and unsafe. Prescription drugs that cause weight loss primarily do so by suppressing appetite or enhancing satiety. Others, however, promote weight loss by inhibiting the digestion of fat. This is dangerous as dietary fat is necessary for vitamin and mineral absorption as well as many important cellular functions.

Plus, many of these obesity drugs cause several uncomfortable side effects, including fatigue, dry mouth, hair loss, sweating, sleep disturbances, dizziness, sexual dysfunction, and high blood pressure.

Dietary supplements that are marketed for weight loss are often poorly studied for their efficacy, and most are ineffective or cause minimal weight loss. Other combinations like ephedrine and caffeine are not approved by the FDA and can cause heart palpitations and jitteriness.

Before trying any weight loss medications or supplements, consult a health care professional. Many over-the-counter diet and weight loss supplements are not regulated and can be dangerous.

6 Science-Backed Ways to Safely Promote Weight Loss

Don't let the negative impact of losing weight quickly deter you from reaching your weight loss goals. There are safe ways to lose weight without putting yourself at risk of any unfavorable health impacts.

Prioritize Protein

In general, Americans meet the recommended daily allowance (RDA) of 0.8 grams of protein per kilogram of body weight; however, they do not embrace variety. The goal should be to increase variety of protein foods and select lean options such as fish, nuts, and chicken, while reducing intake of cold cuts, cured meats, and fatty cuts of beef.

For some active adults, maximizing protein intake to about 1.2 grams of protein per kilogram of body weight might be advantageous. The exact amount of protein you need will depend on your age, activity level, and if you have any health conditions. High protein diets have been shown to increase satiety, reduce overall daily caloric intake, and promote fat loss.

In addition, high protein diets help prevent reductions in lean mass (muscle) and maintain an efficient metabolic rate despite promoting weight loss.

Make Sleep Important

It's often difficult to get quality sleep as an adult due to stress, insomnia, or limited time. However, it's important to note that sleep habits are extremely important for successful weight loss.

A study was conducted on people with sleep apnea who were on a weight loss program. The severity of sleep apnea was accounted for. Researchers found that those with less severe sleep apnea had greater weight loss success than those with poor sleep health. Other studies have shown similar benefits of sleep health on weight loss.

The Centers for Disease Control and Prevention recommends aiming for at least 7 hours of uninterrupted sleep per night. Reducing screen time before bed, eliminating afternoon and evening consumption of caffeine, and engaging in regular physical activity are all ways to improve sleep.

Find Ways to Reduce Stress

Stress might be one of the biggest reasons you can't lose weight. It can throw you off-kilter emotionally and physically and put a damper on your goals. If you can't figure out why your body is not changing, it could be that the stress you're experiencing is out of control.

The impact of stress management on weight loss has not been studied widely; however, the data that does exist is promising. One study, in particular, found that the implementation of a stress management program in obese individuals led to significant reductions in their levels of perceived stress and depression as well as to their adoption of healthier eating habits,

Another study found that those under high stress were less likely to lose weight. On top of that, if you're stressed, you might be more likely to gain weight. All the more reason to work towards reducing stress on a daily basis.

Stress management doesn't have to be time-intensive. Just ten minutes per day is a great way to start working towards less stress. Find things that help you feel good and do that.

10 Ways to Reduce Stress

  • Meditation
  • Take a walk
  • Read a good book
  • Take a bath
  • Do some retail therapy
  • Listen to your favorite music
  • Spend time in nature
  • Try deep breathing
  • Exercise
  • Catch up with a friend or family member

Create a Small Calorie Deficit

No matter which lifestyle you follow, to lose weight, you generally must create a calorie deficit. This means your body is burning more calories than you're eating. However, it's important to note that losing weight is far more complicated than a calorie deficit for many people, and the opinions on this complex subject are varying.

The key is to reduce your calories just enough to see results but not enough to lose weight too rapidly. A great way to do this is to utilize exercise and diet to create a calorie deficit. That way, you only need to reduce your daily calories by about 250 per day to see progress.

Boosting your daily energy expenditure is another way to create a calorie deficit. There are three ways to do so:

Aside from exercise, moving more throughout the day is the best way to increase your daily energy expenditure.

To find out how much you're burning throughout the day, calculate your TDEE (total daily energy expenditure.

Focus on Fiber

High-fiber foods, including whole grains, fruits, and vegetables, are a staple in any diet, particularly those aimed at weight loss. High-fiber foods are more satisfying, which may result in the overall consumption of fewer calories. Ideally, the calories from high-fiber foods would "crowd out" calories from less nutritious items like candy, cookies, and other low-fiber, high-sugar items.

High-fiber whole foods (think 100% whole wheat bread, fresh vegetables, and high-fiber fruits like berries) are recommended over fiber supplements as an effective strategy to promote weight loss. Plus, a diet rich in fruits and vegetables may have favorable effects on cardiovascular and cancer risk factors.

The Adequate Intake for fiber is 25 grams per day for women and 38 grams per day for men.

Incorporate Strength Training

Physical activity is a great way to promote fat loss. Both aerobic and weight-bearing workouts burn calories and contribute to a balanced weight loss routine.

Research suggests incorporating 2-3 days of resistance training produces the same amount of weight loss as aerobic training alone, but that resistance training improves body composition by reducing body fat and increasing muscle mass.

A personal trainer or coach can help you put together a strength training routine that works for your ability and lifestyle. If you don't have access to a trainer or coach, there are a variety of apps, at-home streaming workouts, and other alternatives for incorporating strength training into your routine.

A Word From Verywell

If weight loss is your goal, there are balanced, reasonable, and safe measures to make it happen in a timely manner. Avoid being in a rush to lose weight, as fast weight loss will likely not be sustainable. Instead, remember that slower progress generally produces better results overall.

Talking to a healthcare professional like a Registered Dietitian can help you map out a plan to help you reach your goals in the best way possible. If that's not within your budget, remember to source credible, science-backed programs and coaches that promote safe information, such as recipes created by a registered dietitian or workouts designed by a certified personal trainer.

Frequently Asked Questions

  • How can I reduce my weight naturally?

    Diet and exercise are the best ways to reduce your body weight naturally. Increasing protein and fiber while reducing overall caloric intake may help you to feel energized and satisfied. In addition, increasing your daily energy expenditure by moving more throughout the day may help you expend calories without even noticing.

  • Which is the best weight loss drink?

    Hydration is critical for general bodily function, as well as weight management. While water is generally the best beverage, green tea and coffee may promote weight loss. However, the amount of weight loss associated with green tea is so small it's not really significant from a science standpoint.

  • What should I eat at night to lose weight?

    There's nothing specific that you must eat at night to help you lose weight. Sometimes eating too close to bedtime can cause sleep disruptions that aren't good for weight loss. But if you prefer to eat, evidence suggests that a protein-rich snack is ideal. Some before-bed snack ideas include cottage cheese with pineapple, eggs, a protein shake, or Greek yogurt.

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By Shoshana Pritzker RD, CDN, CSSD, CISSN
Shoshana Pritzker RD, CDN is a sports and pediatric dietitian, the owner of Nutrition by Shoshana, and is the author of "Carb Cycling for Weight Loss." Shoshana received her B.S in dietetics and nutrition from Florida International University. She's been writing and creating content in the health, nutrition, and fitness space for over 15 years and is regularly featured in Oxygen Magazine, JennyCraig.com, and more.