Do Quick Weight Loss Methods Work?

Fit woman measuring her bare midriff with a measuring tape

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People are often tempted by the words “quick weight loss” or “lose weight fast.” Many trendy weight loss programs promise that you will lose weight quickly and keep it off. The problem is that many of those fad “crash” diets aren’t realistic and don’t work.

Losing weight relatively quickly can actually be part of a healthy weight loss plan, but it does depend on the individual. If you want your weight loss to last, however, the fast weight loss phase has to be part of a larger, more comprehensive approach that includes long-term lifestyle changes to help you maintain a lower weight.

Quick weight-loss diets alone don’t provide anyone the opportunity to learn important healthy habits that they need to sustain their goal weight for life. This is why, under the supervision of a healthcare professional, transitioning to a longer-term traditional weight loss plan is important.

Common "Fast" Weight Loss Methods

So how do people lose weight quickly? Common methods include low-calorie diets (LCD) and very low-calorie diets (VLCD). People should know the difference before they choose a weight loss plan. Before attempting these or any weight loss programs, be sure to consult with your doctor.

  • Low-Calorie Diet: Weight loss programs that provide 1,000–1,200 calories per day for women or 1,200–1,600 calories per day for men are considered to be low-calorie diets. According to the Weight Control Information Network, these diets often include regular foods that are sometimes combined with meal replacement shakes or products.
  • Very Low-Calorie Diet: VLCDs are often liquid diets or diets that include little or no regular food. Very low-calorie diets provide up to 800 calories per day. These diets generally require medical supervision and can only be maintained for a short period of time. Patients who are obese may work with their physicians to lose weight on a VLCD, like Optifast, to improve their health.

Popular Diets to Lose Weight Fast

You’ll see some trendy low-calorie diets, including the M-Plan Diet and the 3-Day Military Diet, advertised online and in fashion magazines or tabloids. Their attention-grabbing strategies often appeal to those who are looking for something new and something easy.

These plans are generally not backed by legitimate weight loss companies, physicians or registered dietitians and they are usually not effective for long-term weight loss.

But some low-calorie diets are endorsed by brands that you’d recognize. Nutrisystem, for example, had a Fast 5+ Kit which claimed you will lose five pounds in the first week. During that week, people are instructed to follow a structured eating plan that provides approximately 1000 calories.

In 2013, Dr. Anthony Fabricatore was the Vice President of Research and Development for Nutrisystem. He said that the Fast 5+ Kit is meant to be part of a long-term plan. He explained that “after the first week, customers transition to the calorie level that is tailored to their estimated metabolic needs to support a continued 1-2 pound loss per week.”

But Nutrisystem is not the only commercial diet program to include fast weight loss as part of the first weeks of the plan. Diets like Atkins and The South Beach Diet also include a low-calorie stage in the beginning to boost your weight loss. 

Why (Some) Quick Weight Diets Work

So why would a dieter follow a short-term, low-calorie diet if their rate of weight loss is ultimately going to slow down? According to Fabricatore, short-term quick weight loss can provide a boost to some. In his experience as a clinical therapist, he sees people gain two specific benefits. 

  • Quick (But Not Always Healthy) Results: When people start a diet, they invest time, money and effort. If they get a quick return on their investment, they are more likely to continue to invest and stick to their plan for a longer period of time. However, this isn't always the healthiest option.
  • Positive Beliefs: When a dieter believes that they can lose weight, they boost their chances of reaching their weight loss goal. It’s a concept that psychologists call self-efficacy; the belief that you can carry out a specific task. A week of successful quick weight loss can help you to boost your belief system and build self-efficacy. Of course, you can always increase your positive belief in other ways, such as having a mantra, developing patience, and even recruiting a friend to be a workout buddy.

Quick Weight Loss Drawbacks

Low-calorie diets and very low-calorie diets are not for everyone. Very low-calorie diets are only appropriate for people who are under medical supervision. In most cases, they are used with people who are obese or whose health is at risk because of their weight. Low-calorie diets, like the Fast 5+ Kit by Nutrisystem, are not always medically appropriate for those with diabetes or other medical conditions.

In addition, transitioning off of a low-calorie diet can be problematic. After quick weight loss, you must either switch to a more traditional diet or go back to their old eating habits.

People who go back to their old eating habits are likely to gain the weight back. And those who move to a traditional diet can be disappointed when their weight loss slows down or stalls.

On the other hand, when people invest in a well-balanced comprehensive long-term weight loss plan—that may or may not include a fast weight loss phase—they learn healthy habits like portion control, finding time for exercise and moderation. Ultimately these are the skills that will keep them lean for life. 

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