If you're a woman cutting calories to lose body fat – not muscle – you may want to increase your protein intake. New findings from the University of Illinois suggest that older women who stick to a higher protein weight loss diet – as opposed to a higher carbohydrate reducing plan – not only lose more weight, they also gain more muscle.
Women who diet are at greater risk of losing muscle mass and muscle strength, consequences that could undermine balance, mobility, overall strength and physical performance. Loss of muscle can even impact how well women perform everyday tasks like walking upstairs or getting up from a chair.
Research has shown that older adults who get more protein in their diet are less likely to lose muscle as they age. Yet many women cut back on protein when trying to lose weight.
The study, published in this month's issue of the Journal of Gerontology: Medical Sciences, set out to determine the effect of a higher protein, lower carbohydrate weight loss diet on body weight, muscle mass and physical performance compared with a higher carb, lower protein intake.
The six month trial assigned 31 healthy, overweight women, average age 65 years, to a 1,400 calories a day diet. Half the women received a 25 gram whey protein supplement to be taken once in the morning and again in the afternoon or evening. The other group took a 25 gram carbohydrate supplement twice daily.
The 1,400 calorie protein diet provided 30 per cent of calories from protein, 40 per cent from carbohydrate and 30 per cent from fat. While higher in protein, this diet is not an Atkins-style eating plan. It has a moderate – not low – carbohydrate content.
Women on the 1,400 calorie carbohydrate diet consumed 18 per cent protein, 52 per cent carbohydrate and 30 per cent fat.
Both groups attended two to three exercise classes a week, each consisting of 20 minutes of flexibility exercises and 20 to 30 minutes of brisk walking on an indoor track.
Women who followed the higher protein diet lost 4 per cent more weight and 11 per cent more body fat than their peers on the carbohydrate diet. They also managed to gain almost 6 per cent more thigh muscle which led to better results on physical performance tests. (Incorporating resistance training into a weight loss program would have even greater benefits for strength and physical performance.) These results reveal that a higher protein intake during weight loss can help preserve muscle. Consuming protein in the morning and throughout the day keeps amino acids – the building blocks of protein – always available to muscles.
A higher protein diet also helps put the brakes on hunger, which can improve weight loss results by curbing calorie intake. At the end of the study, women in the protein group were consuming about 1,370 calories a day; while those on the higher carbohydrate diet were eating about 1,625 calories daily.
So how much protein do you need? Sedentary folks need 0.8 grams protein for each kilogram body weight a day. For a 140-pound (64 kg) female, this translates into 51 grams of protein, an amount equivalent to five ounces of chicken and two cups of milk or soy beverage.
It's thought that older adults require one gram of protein for each kilogram a day to slow age-related muscle loss.
(The 1,400 calorie weight loss diet prescribed in the study provided 0.8 grams protein a kilogram plus 50 grams of protein from the supplements.)
Exercise increases protein needs. Endurance athletes need to consume roughly 1.2 grams of protein for each kilogram of body weight a day. Resistance exercise such as weight lifting boosts protein needs to 1.2 to 1.7 grams of protein for each kilogram body weight s day.
Protein-rich foods include meat, poultry, fish, eggs, beans, tofu, soy products, milk, yogurt and cheese.
If you're trying to shed weight, be sure to include protein at all meals and snacks. Doing so can help tame your appetite and preserve muscle mass while losing body fat.
Choose lean protein
To keep saturated fat and calories to a minimum, choose poultry breast, fish, egg whites and lean cuts of meat such as sirloin, tenderloin, extra lean ground beef, pork loin and wild game.
Kidney beans, chickpeas, black beans, soybeans and other legumes have no saturated fat and are a good source of fibre, vitamins and minerals as well as protein. One-third cup of beans has roughly the protein equivalent of one ounce of meat, chicken or fish.
Nuts provide protein too but they're high in calories as a result of their fat content. For example, one-quarter cup of almonds (about 23) delivers 7.5 grams of protein along with 206 calories.
Limit red meat
If you like red meat – beef, veal, pork, lamb – keep your intake to less than 18 ounces a week. Higher intakes have been linked with a greater risk of colon cancer.
Avoid processed meat including bacon, sausage and deli meats because they also have been associated with a higher colon cancer risk.
Don't forget dairy
Milk, yogurt, kefir and part skim cheese are excellent protein sources to include at meals and snacks. One cup of milk supplies eight grams of protein, ¾ cup plain low fat yogurt has 10 grams and ¾ cup of plain kefir delivers about six grams.
Soy beverages are also a good source of protein providing about eight to nine grams in one cup. Rice and almond beverages are not a nutritional replacement for milk because they're low in protein (one to four grams in one cup depending on the brand).
Supplements count too
When you're cutting calories, whey protein power is a convenient way to add extra protein without adding extra calories. While brands vary, most products provide 25 grams of protein and 100 to 120 calories for each scoop (28 grams).
Choose a product that's free of artificial flavours and sweeteners. Avoid brands that contain excess sugar in the form of fructose, dextrose and maltodextrin. Pure whey protein powder should have less than two grams of sugar for every 30 grams of protein.
Whey protein isn't for everyone; it can cause bloating and digestive distress.
Leslie Beck, a Toronto-based dietitian at the Medcan Clinic, is on CTV's Canada AM every Wednesday. Her website is lesliebeck.com.
Protein-packed foods Protein (grams)
Meat, 3 oz. 21-25
Poultry breast, 3 oz. 25
Salmon, 3 oz. 19
Tilapia, 3 oz. 22
Tuna, 2 ounces (about ½ can) 15
Egg, 1 large whole 6
Egg, 1 large white 3
Milk, 1 cup 8
Yogurt, plain, ¾ cup 10
Yogurt, Greek, ¾ cup 18-21
Cheese, hard, part skim, 1 oz. 7
Black beans, cooked, ¾ cup 11.5
Lentils, cooked, ¾ cup 13.4
Soybeans, cooked, ¾ cup 21.5
Tofu, firm, ¾ cup 30
Almonds, ¼ cup 7.5
Whey protein powder,
1 scoop (28 g) 20-30