Come January, many people will be heading back to the gym and cutting calories in an effort to lose weight. But your efforts to slim down may be thwarted if you don't eat enough protein.
According to an Australian study published in this month's issue of Nutrition & Dietetics, eating higher-protein meals (think lean meat, poultry, fish, dairy, eggs and legumes) can improve the body's ability to burn fat among people who are overweight and obese - an effect that can translate into shedding extra pounds.
Previous studies have hinted that higher-protein diets are better able to curb your appetite than traditional high-carbohydrate meal plans. But now it seems that boosting protein can also help your body burn more calories.
In the study, researchers gave healthy adults two protein-enriched meals (35 per cent of calories from protein) and one standard meal (14 per cent of protein calories) which all contained the same number of calories. The high-protein meals differed in the type of carbohydrate they contained - either high or low glycemic. The amount of calories burned after each meal was then measured.
(High-glycemic carbohydrates such as white bread, white rice and refined breakfast cereals are digested quickly and cause a rapid rise in blood sugar and an outpouring of insulin, the hormone that removes sugar from the blood and stores it in cells. Low-glycemic foods such as whole grains, legumes and dairy products release sugar more slowly into the bloodstream and don't produce a rush of insulin.)
The high-protein meals led to the greatest level of fat burning. What's more, there was a clear link between one's body composition and the effect of protein. A higher protein intake led to greater fat burning in people with higher amounts of body fat compared to those with lower body fat. The study showed the glycemic index of a meal had no effect on fat breakdown.
Past research has shown that overweight or obese individuals are less efficient at burning fat than their leaner peers. A high-protein diet may enhance weight loss by modifying the fat-burning deficit seen in obese individuals. Indeed, studies have demonstrated that a protein-rich diet is more effective for people who carry excess weight around their midsection.
There are other ways protein may aid weight loss. People following higher-protein diets report less hunger and an increase in fullness after meals. Scientists speculate that protein causes the brain to receive lower levels of appetite-stimulating hormones.
The body also uses more calories to digest, transport, break down and store protein than forcarbohydrates and fat. As well, high-protein diets help the body use insulin more effectively than high-carbohydrate diets, and that helps promote fat breakdown.
Some experts attribute the weight-reducing effect of a high-protein diet to leucine, an amino acid (a building block of protein) that helps maintain muscle mass. (The greater your muscle mass, the higher your resting metabolism - the number of calories burned to keep your heart, lungs, brain and nervous system functioning.)
While the body makes many amino acids, it relies on food to get leucine. The best food sources include meat, dairy products, poultry, fish and eggs.
So how much protein do you need? The U.S. Institute of Medicine allows for a wide range of protein intake for healthy adults - anywhere from 10 to 35 per cent of daily calories. If you follow a 1,400-calorie weight-loss diet, this translates into 35 to 122 grams of protein. If you eat 2,000 calories a day that means 50 to 175 grams of protein. (One gram of protein contains four calories.)
A higher-protein diet isn't safe for everyone. If you have kidney or liver disease, speak to your doctor before adding more protein to your diet. Not all protein is created equal.
Eating more high-fat meat and dairy products will increase your intake of saturated fat, the type that raises LDL (bad) cholesterol in your bloodstream. A heavy intake of red meat and processed meat is also linked with a greater risk of colon cancer.
Choose proteins such as poultry breast, fish, egg whites, low-fat dairy, legumes and soy.
I'm not advocating eating protein at the expense of other healthy foods - such as an Atkins-style diet that shuns all carbohydrates. Rather, protein should be part of a moderate-carbohydrate diet that includes whole grains, fruit, vegetables and healthy fats such as nuts, seeds and avocado.
And if you want to lose weight, you can't add protein without removing calories elsewhere in your diet.
Start by replacing calories from sweets, soft drinks, juice and refined (white) starchy foods with lean versions of protein. To control your appetite during the day, divide your protein intake among three meals and two snacks.
Not all dieters fare well on a higher-protein diet. Some people feel hungry all the time and do better following a high-carbohydrate diet. The key is finding the mix that's right for you.
The following tips will help you add lean protein to meals and snacks.
Try an egg-white omelette with vegetables and a fruit salad.
Cook oatmeal with skim milk instead of water.
Top a slice of whole grain toast with smoked salmon instead of jam or butter.
Instead of fruit juice, drink a smoothie made with milk or soy milk and frozen berries.
FOR LUNCH AND DINNER
At lunch include 3 to 4 ounces of lean protein such as poultry breast, lean meat, fish, soy foods, or legumes.
At dinner aim for 3 to 6 ounces of lean protein.
Instead of white rice or potato, serve a mixed bean or lentil salad with meals.
Pack portable sources of protein such as a hardboiled egg, part-skim cheese, or yogurt.
Enjoy a serving of edamame (steamed green soybeans).
Choose an energy bar that provides 10 to 20 grams of protein (and less than 3 grams of saturated fat).
Leslie Beck, a Toronto-based dietitian at the Medcan Clinic, is on CTV's Canada AM every Wednesday. Her website is lesliebeck.com.