Many diets promise quick and easy weight loss, but are they a good idea?

Diet plans and strategies to help people lose weight fast include special products, cutting carbohydrates, and fasting. Often, these are ways of cutting calories.

Weight loss and weight management can boost overall health for many people, but losing weight too quickly can be risky. Possible complications include malnutrition, fatigue, and a loss of muscle mass.

According to an article in Frontiers in Genetics, crash dieting can also trigger a rebound effect or cycle of “yo-yo dieting,” in which a person regains the lost weight as soon as they stop the diet.

Here, learn about how crash dieting affects the body and get some tips on lasting weight loss.

close up of feet running as a perosn exercises as a quick way to lose weightShare on Pinterest
Healthful habits, such as regular exercise, may help a person lose weight.

Some people use fasting to lose weight quickly. This can be effective for some people, but it should be a short-term solution.

The body uses three sources of energy to fuel the body: glucose, which comes from carbs, fat, and protein.

Food supplies glucose for cells to use as energy. If food provides more energy than a person needs, the body will store this energy as fat for later use.

When the body needs energy, it first uses its store of glucose, and then it will use body fat.

However, when these sources deplete quickly, the body starts breaking down proteins to make glucose. At this point, muscle mass starts to reduce. This can happen in crash diets, even while the person still has body fat.

According to the Obesity Action Coalition (OAC), if the rate of loss is too fast, it can adversely affect health.

Rapid weight loss and yo-yo dieting may also increase the risk of gallstones, according to the OAC.

An older article in Psychology, Health, and Medicine indicates a link between crash dieting and eating disorders.

If the supply of calories is too low, the body will recognize that it is not getting enough energy. To survive, it will become more efficient at holding onto calories.

When fat stores are low, and the body starts to burn muscle, the basal metabolic rate, or metabolism, will slow down to preserve energy.

The body will burn fewer calories in a day, and weight loss will slow. When this happens, it is easy to lose motivation, abandon the diet, and regain lost weight.

The best way to lose weight is a long-term approach that includes:

The Centers for Disease Control and Prevention (CDC) note that even losing 5–10% of body weight can significantly benefit health. People who lose 1–2 pounds (lb) per week are less likely to put that weight back on later.

The CDC recommend focusing on overall lifestyle — including a healthful diet — for weight loss.

Get some more tips here on how to lose weight naturally.

Caloric requirements depend on how much energy an individual needs.

Current guidelines estimate these will range from 1,600 to 2,400 calories per day for an adult female and 2,000–3,000 per day for an adult male.

Factors affecting a person’s energy needs include:

  • general health
  • lifestyle and activity levels
  • sex
  • height and body build
  • age

When a person wants to lose weight, one way to start is to determine how many calories their body needs to maintain its current weight. Then, the person can reduce the number of calories they consume to ensure their intake is suitable for their needs.

Reducing calorie intake

Reducing excess calorie intake can help a person lose weight.

The National Heart, Lung, and Blood Institute (NHLBI) give the following tips for cutting 150 calories when eating out:

  • drink a glass of water instead of a 12-ounce soda
  • have a half portion of fries instead of medium
  • replace fries with a salad and dressing

Eating 150 calories fewer each day than you use can lead to a 5-lb drop in weight over 6 months, the NHLBI add.

A doctor or dietitian can help individuals decide how far to drop their calorie intake if they need to lose weight. This will vary between individuals. Eating too few calories can be as harmful as eating too many.

Learn more here about how many calories a person needs and how an awareness of calories can help in weight management.

Burning more calories

As well as reducing calories in the diet, people can burn more calories by increasing their activity levels.

According to the CDC, a person weighing 154 lb can burn approximately the following calories during 30 minutes of physical activity:

  • running: 295 calories
  • hiking: 185 calories
  • light yard work: 165 calories
  • walking at 3.5 miles per hour: 140 calories
  • lifting weights: 110 calories
  • stretching: 90 calories

Regular exercise is vital for maintaining good health and muscle tone during weight loss. It can also help lose weight and prevent future weight gain.

Here, learn more about calculating your calorie needs.

A combination of aerobic exercise and resistance training can contribute to effective, long-term weight loss.

Aerobic exercise

Often called cardio exercise, this includes brisk exercise that promotes the circulation of oxygen through the blood and raises the heartbeat.

Examples include:

  • cycling
  • swimming
  • running
  • brisk walking

Resistance training

Resistance training includes weight lifting and body strengthening exercises.

  • induces muscle contractions
  • builds strength
  • increases endurance
  • boosts muscle mass and strength

It is not necessary to use heavy weights. A person can benefit from starting with lighter weights and building up over time.

Before starting resistance training, seek advice from an expert. Exercising too much, too soon, and in the wrong way can lead to injury.

Which is best?

Aerobic exercise burns more calories than resistance training.

Resistance training helps maintain muscle mass, and people with more muscle burn more calories per minute, even while resting.

Experts recommend combining both types. A 2017 study points out that combining both types with a weight loss diet can help reduce frailty, improve physical function, and maintain muscle mass in older adults.

There is no best diet for weight loss. The most effective strategy is to choose healthful lifestyle habits.

Some commercial diet plans can be effective but expensive to follow and hard to maintain. When a person quits the diet, they often regain the weight.

Possible options include:

A Mediterranean diet may be a good option. There is no specific diet plan, but the diet involves:

  • plenty of fresh fruits and vegetables
  • healthful oils, such as olive oil
  • whole grains, nuts, and seeds
  • a low intake of low fat meat
  • fish
  • cheese and yogurt

These foods provide nutrients that can help with weight loss and benefit a person’s overall health. At least one review found it helped people with overweight or obesity to lose weight over 12 months.

The fiber in plant-based foods can help people lose weight in the following ways:

  • the body takes longer to absorb the nutrients, and some fiber passes straight through
  • fiber helps maintain the health of the digestive system
  • a person will feel full for longer and less likely to eat again soon after
  • it can help prevent glucose spikes, which play a role in diabetes, obesity, and other aspects of metabolic syndrome

A 2012 study showed that different diet types might have different effects on metabolic rate.

With more research, these findings could help experts develop more effective weight-loss strategies.

Weight loss is not just a question of eating less but a combination of healthful lifestyle factors.

Many crash diets depend on excessively and rapidly reducing calories, but calorie intake is not the only aim of a healthful diet.

The best strategies usually combine:

  • consuming fewer calories
  • increasing exercise levels
  • making nutritious choices

A diet of fresh foods that contain a range of nutrients is crucial to overall health. Together with regular exercise, healthful dietary choices can contribute to weight loss, even without counting calories.