Many weight loss diets - and even just guidelines for healthy eating - place the emphasis on portion control. If you're still confused about portion sizes, this article is for you.
Food portions for different food groups – adults
a) Milk and dairy products
Milk and dairy products are rich in calcium, high-quality protein and B vitamins, especially vitamin B2 or riboflavin. Use fat-free or skim milk, yoghurt and cottage cheese to obtain all the nutrients without the fat.
One portion of milk is 1 cup or 250 ml. Such a portion of milk will provide about 250-300 mg of calcium.
1 cup of full-cream milk contains approximately 12 g of carbohydrate, 8 g of protein and 10 g of fat (use skim or fat-free milk to lower this fat content).
1 portion of yoghurt is 1 cup or 250 ml.
1 cup of full-cream yoghurt contains approx. 12 g of carbohydrate, 8 g of protein and 8 g of fat (reduce this fat content by eating fat-free yoghurt)
1 portion of cottage cheese is 1/4 cup or 63 ml.
1/4 cup of cottage cheese contains 2 g of carbohydrate, 8 g of protein and less than 1 g of fat (if you use fat-free cottage cheese)
b) Protein foods
Our main sources of high-quality protein, vitamin B12 (prevents pernicious anaemia), other B vitamins and iron and zinc.
1 portion of a protein food provides 7 g of protein, 5 g of fat and hardly any carbohydrate.
Meat and fish:
1 portion is 30 g - most people eat 3 or 4 meat or fish portions at one sitting (meat is relatively high in saturated fat and can push up your cholesterol levels, so use lean meat and cut off visible fat to keep the fat content as low as possible. Fatty fish is so healthy because of its omega-3 content that you can eat larger portions)
1 portion is 30 g (remember that hard cheeses have a much higher fat content than soft cheeses).
1 portion is a 50 g egg. Eggs are rich in high-quality protein, iron (yolk) and if enriched with omega-3 fatty acids, eggs can also boost omega-3 intake. Egg yolk is high in cholesterol, so moderate intakes are advised.
The SA Heart Foundation recommends that South African adults should not eat more than 4 eggs a week. Prepare eggs without adding fat - boil, poach or fry in a non-stick pan sprayed with Spray and Cook.
c) Grains and cereals
This large food group can provide us with plenty of dietary fibre, B vitamins and minerals, provided we eat the unsifted or minimally processed or high-bran varieties.
The portions listed below will provide 15 g of carbohydrate, 2 g of protein and hardly any fat.
Breakfast cereals, dry:
1 portion is 3/4 cup or 20 g (use high-bran varieties to promote regularity and 'dilute' the energy content of the diet).
Breakfast cereals, cooked:
1 portion is ½ cup or 100 g (unsifted maize meal and Maltabella are unprocessed varieties).
Bread and rolls:
1 portion is 1 slice of bread or 1 roll weighing about 25-30 g (select wholewheat, rye, brown or seedbread to increase your dietary fibre intake).
1 portion is 2-3 crackers or about 20 g (select wholewheat or wholegrain products).
Cooked rice, pasta:
1 portion is ½ cup cooked or 100 g (buy brown rice or Durum or wholewheat pasta which have a low glycaemic index).
'5-a-Day' will keep you healthy because vegetables are excellent sources of all the protective nutrients - dietary fibre, vitamins, minerals, bioflavonoids, and will protect you against heart disease and cancer.
1 portion is ½ cup or 100 g.
Starchy vegetables like potatoes, sweetcorn or sweet potatoes also provide 15 g of carbohydrates and 2 g of protein like other starchy foods.
Moderately starchy vegetables:
1 portion is ½ cup or 100 g.
Vegetables such as beetroot, carrots, onion, green peas, pumpkin, winter squash, butternut and turnips are regarded as moderate starch sources. These vegetables provide 7 g of carbohydrate, 2 g of protein and negligible fat per portion.
1 portion is 1 cup or 200g.
Asparagus, green beans, broccoli, Brussels sprouts, cabbage, cauliflower, celery, cucumber, eggplant, spinach, lettuce, mushrooms, okra, sweet peppers, radish, sauerkraut, gem squash, tomatoes and watercress contain so little carbohydrate, protein and fat that they are regarded as 'free' vegetables.
1 portion is 1 small fruit or ½ a banana, or 1 cup of berries, or ½ cup of fruit juice. Very sweet fruit such as dried fruit, dates, and grapes should be eaten in small quantities, e.g. 2 dates and 12 grapes are regarded as a portion.
Like vegetables, these plant foods are brimming with healthy nutrients. 1 portion of fruit supplies about 10 g of carbohydrate and negligible amounts of protein and fat.
Stock up on 'free' fruits such as strawberries and other berry fruits, grapefruit and pawpaw which have a low energy content, but are rich in protective vitamin C, carotenoids and other bioflavonoids.
1 portion is ½ cup or 50 g of baked beans, or ½ cup of cooked legumes or 1 cup of soup made with legumes.
Dried beans, peas and lentils (legumes) are rich sources of dietary fibre and bioflavonoids, and phytochemicals. Use them to reduce your fat intake and improve regularity.
1 portion provides 15 g of carbohydrate, 2 g of protein and hardly any fat.
1 portion of nuts is 15 g
1 portion of peanut butter is 1 tablespoon or 30 g
Nuts are healthy foods that can provide us with plenty of monounsaturated fat to protect our cardiovascular system, but they are rich in energy, so eat them in moderation.
A portion will supply you with 1 g of carbohydrates, 1 g of protein and 12 g of fat.
h) Fats and oils
1 portion is 1 teaspoon of butter, margarine, mayonnaise, salad or cooking oil, or
1 tablespoon of cream, or 1/8 of a medium avocado.
Fats and oils are high in energy, but we do need to include them in moderate quantities in our diets to ensure good health. A portion will provide 5 g of fat (use oils and margarines that have a high mono- or polyunsaturated fat content to ensure heart health).
Photo: Food portion from Shutterstock
The balanced diet
Any questions? Ask DietDoc
Dr Ingrid van Heerden is a registered dietician and holds a doctoral degree in Nutrition and Biochemistry. She believes that "we are what we eat" and offers free nutrition and weight loss advice via her DietDoc service on Health24.com. Read more of her articles.