Weight loss goals vary by individual, but often people want to lose a certain amount of weight within a specific amount of time. If you have a more aggressive goal to lose 20 pounds in two months, it will require a combination of a strict diet and exercise regimen.
How Weight Loss Works
Total energy expenditure (TEE) is made up of resting energy expenditure (REE, what's needed for basic body functions), the energy used during physical activity, and the energy used during digestion. By adjusting your diet and exercise routine, you can affect the number of calories consumed and/or expended to create a calorie deficit result in weight loss.
Read more: Healthy Ways to Lose Weight Fast
Although calorie restriction can result in short-term weight loss, it is not a long-term body weight management plan. A study published in April 2015 in the International Journal of Obesity showed that after weight loss, body functions such as appetite regulation and metabolism adjust to accomodate for a smaller body size. Thus, you cannot keep cutting calories and expect to see the same weight loss results over time. Genetics also play a factor in an individual's weight.
Lose 20 Pounds
To lose 20 pounds in two months, you have you lose about 2.5 pounds per week. According to the Centers for Disease Control and Prevention (CDC), healthy weight loss is in the range of 1-2 pounds per week, as people who lose weight gradually are more likely to keep it off.
However, it may be possible to achieve a 2.5 pound per week weight loss by eating smart and increasing physical activity. Consult a doctor if you have questions about what a healthy amount of weight loss is for you.
It has been widely believed that 3,500 calories are equal to 1 pound of weight. But an article in the December 2014 issue of the International Journal of Obesity found that the 3,500 calorie rule overestimates weight loss. Due to variations in factors including body composition, gender, age, height and amount of calorie restriction, weight loss is not linear like the 3,500 rule would predict.
Instead, researchers recommend a weight loss calculator that takes into consideration various factors to predict an individual's weight loss each week. If you are doing a two-month weight loss challenge, dynamic weight loss calculators can help you estimate how many calories are needed to achieve that goal, for example:
Diet for Weight Loss
Not all calories are equal, so changing the composition of your caloric intake is important to losing weight.
In a review published in April 2015 in the American Journal of Clinical Nutrition, researchers concluded a higher-protein diet was linked to multiple benefits in weight loss. Increased protein is linked to increased energy expenditure, which can help you burn more calories. Protein is also more filling and effective in creating the feeling of satiety (or fullness) compared to carbohydrates or dietary fat, so incorporating more protein into your diet may help you eat fewer calories.
Read more: How Much Protein Is Right For You?
Another study in the American Journal of Clinical Nutrition published in May 2013 found that a normal protein intake of 0.8 grams per kilogram of body weight (as recommended by the Institute of Medicine) is important for initial weight loss and body weight management, however an increased level of 1.2 grams per kilogram of body weight can help maintain REE and fat free mass.
Good sources of protein include lean meats, seafood, poultry, yogurt and eggs, which are all considered "complete" proteins. Complete proteins contain all the essential amino acids your body needs. Incomplete protein sources, which are missing at least one essential amino acid, include plant-based foods such as vegetables, grains, legumes, nuts and seeds. However, you can eat various incomplete proteins to get the benefits of a complete protein source.
Eat Fewer Carbs
In an article in the November 2018 issue of the British Medical Journal, researchers found that participants on a low-carbohydrate diet (defined as 20 percent of total calories) had significant higher TEE than those on a high-carbohydrate diet (60 percent of total calories).
Carbohydrates are an important source of energy for your body, especially if you are physically active. To help lose 20 pounds in two months, you should try to limit refined carbohydrates such as white rice and pasta and focus on fiber-rich, complex carbohydrates such as beans and whole grains.
Dietary fiber can also reduce hunger, decrease caloric intake and help prevent weight gain. For a two-month weight loss challenge, include good food sources of fiber in your diet, such as high-fiber cereals, beans, avocados and apples with skin.
Consume Less Sugar
In a review and meta-analysis published in the British Medical Journal in January 2013, individuals who decreased their consumption of free sugars (sugars added to food as well as the natural sugars in honey, syrups and fruit juices) and sugar-sweetened beverages lost body weight. This was due to reductions in overall caloric intake; when subjects replaced high-sugar foods with low-sugar alternatives, the same body weight changes were not found.
In addition to being linked to obesity, eating too much sugar can also increase the risk of type 2 diabetes and heart disease. The CDC recommends adults limit their intake of added sugars to 10 percent of total calories.
As part of a two-month weight loss challenge, an easy way to cut down on your sugar and calories is to eliminate soda and fruit juices from your diet and replace them with water. This can help you consumer fewer calories in general, which is helpful with weight loss.
Increase Water Intake
Proper hydration is important for overall health and body function, but there is also some evidence that water can help you lose weight. In a study that appeared in the July 2016 issue of the Annals of Family Medicine, researchers found that increased inadequate hydration was linked to elevated BMI and obesity.
The daily recommended water intake (water from both food and beverages) is 91 ounces and 125 ounces for adult women and men, respectively. Individual needs vary by climate, age, gender and activity level.
Exercise for Weight Loss
The CDC recommends that adults who want to maintain their weight engage in 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity aerobic activity per week. This can be spread over the week and you can mix both moderate- and vigorous-intensity activities. To lose weight, you should increase this amount to help create a calorie deficit.
A moderate-intense activity is defined as an activity where breathing and heart rate are accelerated but you can still have a conversation. These could include a brisk walk or casual bike ride. A vigorous-intense activity is one where your heart rate is up and your breathing is hard. These include running, swimming laps, hiking uphill or high-intensity interval training (HIIT). The CDC has estimates of calories used in a variety of moderate and vigorous activities.
The U.S. Department of Health and Human Services' Physical Activity Guidelines for Americans also recommends adults do muscle-strengthening activities at least two days per week. In addition to burning calories, regular exercise can help reduce the risk of chronic diseases such as type 2 diabetes, cardiovascular disease and some types of cancer.
In an review published in October 2013 in Progress in Cardiovascular Diseases, researchers found that calorie restriction is more effective than physical activity for weight loss. However, physical activity has other health benefits and can help increase TEE and prevent future weight gain.
Sleep for Weight Loss
A lack of sleep has also been linked to obesity. An article in the May 2013 issue of the American Journal of Human Biology showed that sleep deprivation can lead to increased caloric intake and weight gain. A lack of sleep (generally, fewer than six hours of sleep) can lead to decreased physical activity and lower energy expenditure, which can also lead to weight gain. Thus, an important component of a two-month weight loss challenge should include a good night's sleep.
- International Journal of Obesity: "Physiological Adaptations to Weight Loss and Factors Favouring Weight Regain"
- Office of Disease Prevention and Health Promotion: "Dietary Guidelines for Americans, 2015-2020: Appendix 2. Estimated Calorie Needs per Day, by Age, Sex, and Physical Activity Level"
- Centers for Disease Control and Prevention: "Finding a Balance: Balancing Diet and Activity to Lose and Maintain Weight"
- ChooseMyPlate.gov: "My Plate Plan"
- Centers for Disease Control and Prevention: "Losing Weight: What Is Healthy Weight Loss?"
- International Journal of Obesity: "Why Is the 3500 Kcal per Pound Weight Loss Rule Wrong?"
- Pennington Medical Research Center: "Weight Loss Predictor"
- Pennington Medical Research Center: "Single Subject Weight Change Predictor"
- National Institute of Diabetes and Digestive and Kidney Diseases: "Body Weight Planner"
- American Journal of Clinical Nutrition: "The Role of Protein in Weight Loss and Maintenance"
- Institute of Medicine: "Dietary Reference Intakes: Macronutrients"
- British Medical Journal: "Effects of a Low Carbohydrate Diet on Energy Expenditure During Weight Loss Maintenance: Randomized Trial"
- Journal of Nutrition and Metabolism: "Dietary Fiber Intake among Normal-Weight and Overweight Female Health Care Workers: An Exploratory Nested Case-Control Study within FINALE-Health"
- Harvard Health Publishing: "Carbohydrates — Good or Bad for You?"
- British Medical Journal: "Dietary Sugars and Body Weight: Systematic Review and Meta-Analyses of Randomised Controlled Trials and Cohort Studies"
- Centers for Disease Control and Prevention: "Know Your Limit for Added Sugars"
- Centers for Disease Control and Prevention: "Get the Facts: Drinking Water and Intake"
- Centers for Disease Control and Prevention: "Physical Activity for a Healthy Weight"
- U.S. Department of Health and Human Services: "Physical Activity Guidelines for Americans, 2nd Edition"
- Progress in Cardiovascular Diseases: "The Role of Exercise and Physical Activity in Weight Loss and Maintenance"
- American Journal of Human Biology: "Does Inadequate Sleep Play a Role in Vulnerability to Obesity?"
- Harvard T.H. Chan School of Public Health: "Sleep:
- American Journal of Clinical Nutrition: "Normal Protein Intake Is Required for Body Weight Loss and Weight Maintenance, and Elevated Protein Intake for Additional Preservation of Resting Energy Expenditure and Fat Free Mass"
- Annals of Family Medicine: "Inadequate Hydration, BMI, and Obesity Among US Adults: NHANES 2009-2012"