People gain weight by consuming more energy than they burn, so consuming fewer calories, or energy, can help. However, other factors play a role, such as metabolism, hormones, the type of food you eat, your body type, and lifestyle.
This article will look at the reasons to lose weight, the most effective methods and medical interventions.
Here are some key points about losing weight. More detail and supporting information is in the main article.
- In basic terms, to lose weight you must burn off more calories than you consume
- Weight-loss supplements do not work
- Diets combined with exercise are much more effective
- Currently, more than one-third of Americans are obese
- A sedentary adult aged 31-50 should consume 2200-2400 calories or less, daily
- A diet needs to contain the right ratios of carbohydrate, protein and fat
- Crash diets may have short term results but are unlikely to be successful in the long run
- Sleeping for 7 or 8 hours a day may help with weight loss
- Bariatric surgery should be a last resort for obese patients.
More than 1 in 3 Americans are obese.
America, and further afield, is facing a type of epidemic never before witnessed by humanity. For the first time in humanity's history, more people are dying from illnesses related to overeating than malnutrition.
The Centers for Disease Control and Prevention (CDC) estimate that more than a third of Americans are currently obese (34.9%). They also estimate that the annual medical cost of obesity in 2008 was $147 billion.
The health risks of being overweight are well documented and include an increased risk of diabetes, stroke and certain types of cancer. If you were planning on losing weight, now is as good a time as any.
People lose weight for many different reasons:
- Appearance - they want to look fitter, more attractive or healthier, or simply feel more confident in their bodies.
- Overall health - they want to become healthier, live longer, and avoid developing diseases associated with obesity and overweight
- For a specific condition or illness - obese people with sleep apnea who lose weight have less severe symptoms - sometimes the sleep apnea goes away completely. Obese or overweight individuals with diabetes type 2 will usually have less severe symptoms if they can bring their weight down to healthy levels. One study found that overweight and obese males with diabetes type 2 who lost weight reported enhanced libidos.
- Fitness - to become fitter, to have more energy and stamina
- Sports competitions - a boxer, for example, may wish to lose weight so that he can remain within his weight category
- Fertility - obese women who are finding it hard to get pregnant sometimes are more likely to do so if they lose weight
Negative Energy Balance - in order to lose weight you need to be exerting more energy than you are consuming; this is called a negative energy balance. If you are in a state of negative energy balance, your body will seek out stores of energy, such as fat or muscle to make up for the shortfall - it will start using up your excess weight. In extreme cases, however, when the individual has little fat, more muscle and lean tissue will be used up.
Sports - some sportsmen and sportswomen will try to lose weight even though doctors would say their body weight is ideal. In some cases it might be to get better speeds or, as mentioned above, to be within a weight classification for a competition.
Losing too much weight - if you become underweight, there are also certain health risks. Your chances of developing infections might increase, there is a risk of osteoporosis, reduced muscle mass and strength, and problems regulating your body temperature. There may even be a higher risk of death if your weight goes down a lot.
There are thousands of different diet plans on the market that make amazing weight loss claims. Some of them are well thought out, safe and effective, while others are not. Most health care professionals, dietitians and nutritionists agree that a combination of a weight-reduction healthy diet with physical activity tends to have the best results, especially in the long term.
Related reading: The eight most popular diets today
Proponents of many diets say they are extremely effective and require no effort at all. Unless they have been proven to be so in scientific studies, it is not possible to know how effective they really are.
The amount of calories a person needs depends on their age, gender and level of daily activity.
The number of calories per day you should consume in order to lose weight depends on several factors, including your sex, how much you want to lose, how quickly you want to lose it and your age.
Below are some estimated figures on how many calories the average person in the USA, Canada and Western Europe should consume in order to maintain their weight (neither put on nor lose weight).
Daily recommended calorie consumption for males:
- Age 19-30
Sedentary - 2400-2600
Moderately active - 2600-2800
Active - 3000
- Age 31-50
Sedentary - 2200-2400
Moderately active - 2400-2600
Active - 2800-3000
- Age 51+
Sedentary - 2000-2200
Moderately active - 2200-2400
Active - 2400-2800
Daily recommended calorie consumption for females:
- Age 19 to 30
Sedentary - 1,800 to 2,000
Moderately active - 2,000 to 2,200
Active - 2,400
- Age 31-50
Sedentary - 1,800
Moderately active - 2,000
Active - 2,200
- Age 51+
Sedentary - 1,600
Moderately active - 1,800
Active - 2000 to 2,200
If you want to lose weight, you would have to consume a little bit less than the amounts listed above. The less you consume, the faster you lose. However, it is important to follow a healthy, well-balanced diet so that you do not become ill, or lose lean tissue (muscle). Ideally, you should check with a dietitian, nutritionist or your doctor.
In some regimes, dieters consume 1,200 calories per day if they are female and 1,500 if they are male. However, do not try to do this yourself without the supervision of a trained expert.
You need to make sure your carbohydrate, protein and fat ratio is right for good health. Recommendations vary, from 20-60% carbohydrate intake for losing weight.
Some studies found that not only do people risk malnutrition if their diet is not well planned, but also loss of motivation. Most dieters drop out before reaching their target weight.
When dieters have reached their target body weight, they should gradually increase their daily intake until they reach their "weight maintenance" figure.
A 2010 study by researchers at Oregon Health & Science University showed that people who just reduce their daily calorie intake rarely lose much weight.
The researchers explained that natural compensatory mechanisms in the body reduce a person's physical activity as soon as calorie consumption drops - in other words, the body slows right down if you eat much less. Dieting must be combined with exercise.
Study leader Judy Cameron said:
"In the midst of America's obesity epidemic, physicians frequently advise their patients to reduce the number of calories they are consuming on a daily basis. This research shows that simply dieting will not likely cause substantial weight loss. Instead, diet and exercise must be combined to achieve this goal."
In response to a reduction in calories, the human's natural body mechanism goes into "conservation mode." Without exercise, there simply will not be much weight loss, they emphasized.
Sleep deprivation can increase weight gain.
Body weight control is much more successful if you can combine a well-balanced diet with regular exercise. Crash diets may have positive short-term results but tend to have poor long-term success rates.
If you manage to sleep between 7-8 hours continuously each 24 hour period, your body weight control will be more successful. Sleep deprivation or lack of sleep can make you put on weight.
A 2008 study published in the journal SLEEP found that a consistent pattern of increased odds of being a short sleeper if you are obese, both in childhood and adulthood.
According to the National Weight Control Registry (NWCR), after combining successful weight loss strategies of 6,000 individuals, the following measures should be taken to make sure you do not put the weight back on:
- Physical activity - do at least 200 minutes each week of moderate-intensity exercise. This should be spread out over at least three days (do not do all the minutes in one go each week).
- Watching TV - limit your TV watching to no more than 10 hours each week. Many people might find this recommendation particularly difficult to follow.
- Fat limit on diet - make sure that no more than 30% of your nutritional intake is in the form of fat.
- Eat consistently - resist the urge to overeat during weekends and holidays. Your food intake should follow a regular routine. Overeating not only upsets your routine, it most likely impacts on your metabolism.
- Breakfast - never miss it. Breakfast is a crucial meal; it also helps stave off hunger later on in the day, which often leads to overeating and snacking.
- Monitor yourself - keep a close check on what you eat and regularly weigh yourself.
Weight and health
Some health care professionals and researchers disagree that doctors, sports therapists and other experts should focus on weight loss when advising their patients and clients. They believe that dieting and weight-loss efforts frequently lead to weight gain and poorer health.
A nutritionist from UC Davis, USA, and a dietician who works in the National Health Service, UK, published a study in the Nutrition Journal in 2011 which showed that rather than concentrating on weight loss, people should focus on better health status, and that the latter results in better body weight control over the long term.
Linda Bacon, of the University of California, Davis Department of Nutrition, said:
"Although health professionals may mean well when they suggest that people lose weight, our analysis indicates that researchers have long interpreted research data through a biased lens.
When the data are reconsidered without the common assumption that fat is harmful, it is overwhelmingly apparent that fat has been highly exaggerated as a risk for disease or decreased longevity."
Several studies have shown that weight-loss supplements have no impact on a dieter's target of losing weight. Scientists from Oregon State University revealed that the concept of supplements aiding weight loss is a myth.
The team reviewed several studies on hundreds of weight loss supplements and found absolutely no evidence that any of them worked. In fact, many may be bad for the health.
Green tea, fiber and low-fat dairy supplements were associated with a slight weight loss in studies where the participants were on a low-calorie diet. All the evidence pointed to the low-calorie diets as having an impact on losing pounds, rather than the supplements. There is no study so far that clearly shows that a supplement alone helps a person lose weight.
The team looked at four categories of supplements: products that block fat absorption, such as chitosan, stimulants like caffeine or ephedra, linoleic acid containing supplements that marketers claim alter the body's composition by decreasing fat, and soluble fibers which are supposed to be appetite suppressants.
Bariatric surgery is performed on dangerously obese people.
Most doctors of severely obese individuals, as well as the patients themselves, find the challenges of reducing weight extremely frustrating.
Bariatric surgery has been found to be the most effective way of achieving weight loss for severely obese people. The procedure results in the greatest reduction in cardiac and other disease risk.
Bariatric surgery, also known as weight loss surgery, is a surgical procedure which is performed on dangerously obese patients; the aim is to make them lose weight.
The stomach is either reduced in size with a gastric band, or some of it is surgically removed. In some cases, gastric bypass surgery is recommended, in which the small intestines are rerouted to a small stomach pouch. After the procedure, the patient's appetite is considerably reduced and they cannot absorb or digest food as fully as before.
One study showed that bariatric surgery is better than dieting for glucose control.
It is important that you aim for an ideal body weight that is compatible with your height, age and sex. This article may help you decide: What is my ideal weight?
A number of genetic factors may influence how people gain weight, according to research published in the journal Obesity.
For the first time, scientists have uncovered a direct link between a gene and fat production in the body - a discovery that may hold the key to tackling obesity.