Weight Loss by Limiting Calories
Losing weight safely means balancing protein, fat, and carbohydrate with every meal and snack. You'll feel fuller longer as your body takes its time digesting the food. There is no perfect method for weight loss, but it helps to have a guide. Choose foods from Canada's Food Guide, including vegetables and fruits, grain products, milk and alternatives, and meat and alternatives.
- Limit fat intake to no more than 20% to 35% of your total calorie intake. For a person following a 1,800-calorie diet, this means eating no more than 40 to 70 grams of fat each day.
- Choose healthy sources of carbohydrates, such as whole grains, whole fruits, and vegetables. About 45% to 65% of your total calorie intake should come from carbohydrate. For someone following a 1,800-calorie diet, this means eating about 200 to 300 grams of carbohydrate each day.
- Choose low-fat protein sources, such as fish, poultry, low-fat milk and alternatives, and legumes (for example, pinto beans, lentils, and split peas). About 10% to 35% of your total calorie intake should come from protein. For someone following a 1,800-calorie diet, this means eating about 45 to 160 grams of protein each day.
- Get enough fibre each day. Include 25 to 38 grams of fibre a day.
- Limit alcohol. Alcohol does not provide any nutrients your body needs and can contain a lot of calories.
If you need some help making your meals and snacks balanced, a dietitian can help you create a plan that fits your lifestyle. Also, you can look at the nutrition facts label to figure out the fat, carbohydrate, and protein in foods.
The more active you are, the more calories you need. When you are less active, you need fewer calories. How many calories you need each day also depends on your age, whether you are male or female, and your activity level.footnote 1 Some life situations, such as being pregnant or breastfeeding, can also influence calorie needs. For more information about your calorie needs, go to Health Canada's webpage for estimated energy requirements at www.hc-sc.gc.ca/fn-an/food-guide-aliment/basics-base/1_1_1-eng.php.
Very low-calorie diets
Use extreme caution with a very low-calorie diet (VLCD). You are starving your body. VLCDs generally are not recommended. Regaining weight is almost certain, which is damaging both physically and psychologically. If you need to lose weight, it is better to lose weight slowly. You will be more likely to lose the weight safely and keep it off.
Although initial weight loss is greater on a VLCD than on a low-calorie diet, in the long term about the same amount of weight is lost in both types of diets.footnote 2
Diets this low in calories (less than 1,000 calories a day) generally do not provide enough nutrients for good health unless the diet is specially prepared. You will need the assistance of a health professional. A diet that does not have enough vitamins or minerals can lead to serious, potentially fatal health problems.
These diets are not recommended if you have heart problems, blood clotting problems, bleeding ulcers, liver disease, kidney disease, or cancer or if you have had a stroke. If you are older than 50, you will need frequent monitoring by your health professional to be sure you are losing fat and not muscle.
People on these diets often feel tired or have constipation, nausea, or diarrhea as a side effect.
The most common serious side effect is developing gallstones. People who are obese are more likely to develop gallstones than people who are lean, and when a person who is obese uses a very low-calorie diet, the chance that he or she will develop gallstones becomes even greater. People who lose a large amount of weight quickly are at greater risk than those who lose weight more slowly. But you can take medicine that helps prevent gallstones from forming.
The following are the changes your body goes through during a VLCD:
- To get the carbohydrate it needs, your body breaks down protein. You lose lean body tissues (muscle and organ tissue). It is important to preserve lean tissue, because it increases your basal metabolic rate. Losing too much lean tissue increases the percentage of fat in your body. The result is a reduced metabolism. This is one reason why it is so easy to regain weight after you lose weight quickly.
- In a VLCD (or during starvation), about half the weight you lose is fat and the other half is lean tissue, such as muscle. On a more moderate diet, you lose 3 times more fat than lean tissue. It is important to preserve lean tissue, since it increases your resting metabolic rate. This is one reason it is so easy to regain weight when you lose weight quickly
- Mineral and electrolyte imbalances can occur. These imbalances can be life-threatening. This is the reason these VLCDs must only be used under a health professional's supervision.
- Bone mass is lost. This is more risky for women, because they diet more often than men, and they are also at higher risk for osteoporosis.
- Health Canada (2011). Canada's Food Guide: Estimated energy requirements. Available online: http://www.hc-sc.gc.ca/fn-an/food-guide-aliment/basics-base/1_1_1-eng.php.
- American Gastroenterological Association (2002, reapproved 2008). AGA technical review on obesity. Gastroenterology, 123(3): 882-932. [Erratum in Gastroenterology, 123(5): 1752.]
Primary Medical Reviewer Anne C. Poinier, MD - Internal Medicine
Adam Husney, MD - Family Medicine
Kathleen Romito, MD - Family Medicine
Specialist Medical Reviewer Rhonda O'Brien, MS, RD, CDE - Certified Diabetes Educator
Colleen O'Connor, PhD, RD - Registered Dietitian
Current as ofOctober 9, 2017
Current as of: October 9, 2017
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