Literature about healthy diet and its impact on human health and disease prevention is more extensive now than ever before, yet the incidence of diet-related disease keeps rising. Unhealthy eating patterns, and physical inactivity collectively account for 21% of premature deaths in 2016. That’s more than 11 million deaths.27

Economic development has consequences for the diet and lifestyles of individuals, not all of which are positive. The so-called nutrition transition includes shifts in diet towards energy dense foods, processed foods, more fat and sugar, and reduced intake of dietary fiber, fruit and vegetables. 71, 80

The exact composition of a balanced and healthy diet may vary depending on factors such as age, gender, physical activity, religious restrictions, cultural customs and availability of different foods, but the basic principles of what constitutes a healthy diet remain the same.

Let’s take a look at these principles!



A healthy diet must satisfy our needs for energy and all essential nutrients. Daily energy requirements, or the total number of calories a person needs, depends on several factors, including the person’s age, sex, height, weight, and physical activity.

If energy intake is consistently diverging from a person’s requirement, a change in body energy stores, and weight can be expected. A caloric deficit or surplus may help lose, or gain weight, but if the imbalance continues over longer period of times, physical, mental, emotional, and social health and performance may be adversely affected. 19, 20, 51

BOTTOM LINE: A healthy diet has to provide daily energy requirements, but should not create an unwanted calorie shortage or surplus, except for the period during which specific goals require a calorie deficit or excess.

QUICK HELP: A simple equation to calculate Estimated Energy Requirement (EER)  for weight maintenance developed by the Institute of Medicine (US): 37

EER for Men Ages 19 Years and Older (kcal/day):
662 – (9.53 × A) + PA × (15.91 × W + 539.6 × H)

EER for Women Ages 19 Years and Older (kcal/day):
354 – (6.91 × A) + PA × (9.36 × W + 726 × H)


A is age in years

W is body weight in kilograms

H is height in meters

PA is the physical activity coefficient:
PA = 1.00 sedentary lifestyles
PA = 1.11 moderately active lifestyles
PA = 1.25 active lifestyles
PA = 1.48 very active lifestyles

Total Calories that a 32 years old man who is 1,78 m tall, weight 75 kg, and live a moderately active lifestyle, with sedentary job, and half an hour moderate intensity exercise per day, requires in order to maintain his current weight: EER = 662-(9,53×32) +1,11×(15,91×75+539,6×1,78) = 2748 kcal per day

This result should be modified if specific goals are set (i.e. during weight-loss dietary interventions)

The best way to determine and control an appropriate level of calories is to regularly monitor weight, and adjust calorie intake or expenditure (via physical activity) based on changes in body weight over time.



It is not only total number of calories that are important, but also the substance from which the calories are taken. One of the most fundamental challenges for nutritionists is how to convert complex scientific knowledge into easily understood and simple messages about healthy eating.

Food-based dietary guidelines or healthy eating guidelines are simple, practical, science-based messages on healthy eating aimed at preventing all forms of malnutrition and keeping people well-nourished and healthy. These guidelines translate healthy eating messages, and nutrient recommendations into simple information that the public can easily understand, and apply in everyday life.

Nutrition guides typically divide foods into several groups, and recommend daily servings of each group. Foods listed in the same group share similar nutritional properties, and provide similar amounts of key nutrients. Each food group is the major contributor of at least one nutrient while making significant contributions of many other nutrients.

BOTTOM LINE: To meet nutrient needs within our individual calorie limits, we should choose a variety of nutrient-dense foods across and within all food groups in recommended amounts.



Adequate consumption of vegetables and fruit are vitally important to human health as sources of nutrients and non-nutritive food constituents. Statistics show that average daily consumption of vegetables and fruits is far below the recommended daily amounts.1, 7, 17, 24 National Diet and Nutrition Survey in the UK showed that only 31% of adults and 37% of older adults met the “5-a-day” recommendation. 24 In the U.S., just 1 in 10 adults meet the federal fruit or vegetable recommendations, according to CDC’s Morbidity and Mortality Weekly Report. 43

Low consumption of vegetables and fruit contributed to more than 3.8 million deaths in 2016!27

A comprehensive review, that combines the results of 95 studies, found that there was a 16% reduction in the risk of heart disease, a 28% reduction in the risk of stroke, a 22% reduction in the risk of cardiovascular disease, a 13% reduction in the risk of cancer, and a 27% reduction in the risk of all-cause mortality for an intake of 500 g of fruits and vegetables per day, compared to 0–40 grams per day. 1, 55, 56, 70, 80

BOTTOM LINE: Fruit and vegetables should make up over a third of the food we eat each day. The World Health Organization (WHO) recommends eating at least five 80 g portions of fruit and vegetables every day (total 400 grams per day). 55, 56, 80

This amount should be the minimum quantity. Note that in the WHO recommendation potatoes, sweet potatoes, cassava and other starchy roots are not classified as vegetables, and not included in the “400 grams per day” limit. 55, 56, 80

 QUICK HELP: A couple practically measured examples for 1 serving of vegetables and fruit, that may weight about 75-100 grams: 50, 55, 56, 70

1 cup green leafy or raw salad vegetables, such as lettuce, mustard greens, collard greens, cabbage, Swiss chard, spinach, watercress, arugula, endive, escarole etc.

half cup chopped or florets raw or cooked vegetables such as broccoli, cauliflower, brussels sprout, carrots, turnip, celery root, beetroot, cucumber, summer and winter squash, eggplant, radish, daikon etc.

half cup cooked dried or canned beans, peas or lentils

1 medium tomato or a small bell or green pepper

1 small apple, peach, pear, orange, banana, or similar sized fruits

2 small mandarin, apricots, kiwi fruits, plums or similar size of fruits

1/2 cup of berries, including blueberry blackberry, cranberry, strawberry, raspberry, red and white currant etc.

Current recommendations are even higher in Sweden (500 g/day), Denmark (600 g/day), Norway (650–750 g/day), the U.S. (675-800 g/day), and Australia (675-750 g/day). 4, 32, 50, 70

Studies suggest that these increased levels may exert a higher protective effect against adverse health conditions. In the review mentioned above, the lowest risk for all types of cancer was observed at an intake of 600 grams per day (7,5 servings/day). For heart disease, stroke, cardiovascular disease and all-cause mortality, the lowest risk was observed at 800 grams/day (10 servings/day). 4, 32, 50, 55, 56, 70, 80



The grains food group includes grains as single foods, as well as products that include grains as an ingredient, such as breads, pasta, cereals, crackers etc. Foods in this group come from cereal grains like wheat, millet, fonio, maize (corn), sorghum, barley, oats, rice, wild rice, rye, spelt, teff, triticale, and pseudocereal grains such us amaranth, buckwheat, quinoa, kañiwa, kiwicha.

Grains may be either whole or refined.

  • Whole grains contain the entire kernel, including the endosperm, bran, and germ, and are valuable sources of nutrients including fiber, vitamin A, vitamin E, vitamin B1, B2, B6, niacin, selenium, zinc, copper and magnesium. 66
  • Refined grains are modified from their natural state. Generally it involves removal of the bran and germ, which decreases nutrients and fiber.

Studies support the notion that whole grains may protect against cancer (especially gastrointestinal cancers such as gastric and colonic cancer), cardiovascular disease and the development of type 2 diabetes. 2, 23, 47, 62, 65, 72

A comprehensive review, that analyzes the results of 19 individual studies found that the risk of all-cause mortality decreased by 21% with increasing intake of whole grains up to 90 grams per day compared with no consumption of them. 61 But, studies indicate that average consumption of whole grains is far less than recommended levels. 57, 66

BOTTOM LINE: Healthy eating includes whole grains, and limits the intake of products made with refined grains, especially those high in saturated fats, added sugars, and/or sodium such as cookies, cakes, and snack foods. At least half of all grains eaten should be whole grain.

NOTE: This group (beside of starchy vegetables, fruits, and legumes) represents one of the main sources of carbohydrates in our diet. It is recommended that 45 to 65% of daily calories should come from carbohydrates. The recommended number of servings varies depending on the different calorie needs.37, 70, 89 Increase the consumption of whole grains at the expense of refined grains in accordance with your daily calories limits, and carbohydrate needs.

Despite of the individual variances, nutritional guide of health organizations may contain recommendation for this food group also. For example:

  • MyPlate recommend 5-7 ounce-equivalents of grains per day for adults, with at least half being whole grains. (1 ounce-equivalent equals a half cup cooked or 1 ounce (28g) dry rice, oats, bulgur, or other grain, half cup cooked or 1 ounce (28g) dry pasta, 1 regular slice or 1 small slice (French) of bread, 4 snack-size slices rye bread, half English muffin, 1 mini bagel)70
  • The Australian Guide to Healthy Eating suggests at least 4-6 servings of grain per day for adults. (1 serving is equivalent to 1 slice (40g) bread, half a medium (40g) roll or flat bread, a half cup (75-120g) of cooked rice, pasta, noodles, barley, buckwheat, semolina, polenta, bulgur or quinoa, porridge, 1/4 cup (30g) muesli, 3 (35g) crispbreads, 1 (60g) crumpet, 1 small (35g) English muffin or scone.)50

 QUICK HELP: for the carbohydrate content of several carb rich sources:

2 tablespoons (24-26 grams) of uncooked rice, bulgur, millet, pearl barley, amaranth, buckwheat, kamut, couscous, quinoa contains about 18-20 grams of carbs

2 tablespoons (18 grams) of wheat-, barley, oat-, millet-, buckwheat corn flour contains about 14-16 grams of carbs.

1 small slice of wheat bread (22-28 grams) contains about 12-16 grams of carbs (It should be noted that the exact weight and carb content may be highly variable depending on the exact type of bread)

1 average sized bread roll or bagel (55 grams) contains about 30 grams of carbs.

1 cup of raw diced or cubed potato, sweet potato (150 grams) contains about 30 grams of carbs.

1/3 cup of raw beans (50 grams) contains about 30 grams of carbs.

1 cup of sweet corns (145 grams) 35 grams of carbs.

1 cup of green peas (145 grams) 20 grams of carbs.

1/4 cup of raw lentils, chickpeas, split peas (50 grams) contains about 25-30 grams of carbs

1 cup of raw diced or carrot, beetroot (145 grams) contains about 15 grams of carbs.



Dairy products have been part of the human diet for some 8000 years. Due to their nutritional properties, they are included in the nutritional guides of most of health authorities. 60

Dairy products provide a wide range of nutrients that may be difficult to obtain with limited or no dairy consumption. Aside from protein, nutrients concentrated in dairy foods include calcium, magnesium, zinc, phosphorus, and vitamin D. 10, 31, 33, 60 In balanced omnivore diets, dairy products contribute around 52–75 % of the reference intake of calcium. 12, 22, 64, 67, 73, 76

Using data from the National Health and Nutrition Examination Survey (NHANES), researchers concluded that adequate calcium intake cannot be met with dairy-free diets in adolescents, while meeting other nutrient recommendations. 26

BOTTOM LINE: Recommendations include the consumption of 2 to 3 servings of dairy products (500-750 ml of milk, or equivalent dairy products) per day – an amount that provides three-quarters of the recommended daily intake of calcium for the general population.50, 55,56, 70

Individuals who are lactose intolerant may choose lactose-free dairy products. Those who are unable, or unwilling to consume dairy products should be aware of which foods provide the range of nutrients generally obtained from dairy. The nutrients most at risk in dairy-free diets are calcium, and magnesium. 10, 26, 60, 76

Non-dairy sources of calcium, including green leafy vegetables and legumes, may contain compounds such as oxalic acid and phytic acid, that inhibit calcium absorption. For example, cooked spinach contains about 115 mg of calcium per serving, but only 5 % of this is absorbed. Spinach contains a high level of oxalates which bind calcium and form insoluble salt compounds.76

Foods with high levels of oxalic acid include spinach, collard greens, sweet potatoes, rhubarb, and beans. Fiber-containing whole-grain products, wheat bran, beans, seeds, nuts, and soy isolates are high in phytic acid. 38

 QUICK HELP: Examples for a serve of milk and dairy products and alternatives:

1 cup of milk, yogurt, pr kefir
2 slices or 4 x 3 x 2cm cube (40g) of hard cheese
½ cup (150 g) of ricotta cheese
1 cup soy, rice or other cereal drink with at least 100mg of added calcium per 100ml

Amount needed from alternative sources of calcium to provide equal amount of absorbable calcium than 1 cup (240 ml) milk: 76

White beans ~430 grams
Bok choy ~195 grams
Broccoli ~320 grams
Chinese cabbage flower leaves ~85 grams
Chinese mustard greens ~95 grams
Chinese spinach ~280 grams
Kale ~270 grams
Spinach ~1385 grams
Sweet potatoes ~1600 grams
Rhubarb ~1140 grams
Tofu with calcium ~150 grams



Aside from dairy, which may provide 11-15% of our daily protein consumption 34, 53, this food group represents the main protein source in human diet.

The wide variety of foods in this group includes lean meats, poultry, fish, eggs, nuts, seeds, legumes and beans, including soy products. Due to their quality protein content, dairy foods are also considered protein foods, but are treated separately in most of healthy eating guides, because of dairy’s unique nutrient profile.

Aside from protein, the foods in this group are a good source of many nutrients, including B vitamins, iron, zinc and other minerals. Nutrient profile, however, can vary between sources.

  • Meat includes all forms of beef, pork, lamb, veal, goat, and non-bird game, while poultry includes all forms of chicken, turkey, duck, geese, guineafowl, and game birds. Along with eggs, these foods are our main source of Vitamin B12. They also provide zinc, and heme iron, which is more bioavailable than the non-heme iron, found in plants.
  • Eggs are a good source of protein, vitamin D, vitamin A, vitamin B2, B12 and biotin. Eggs provide the most choline, a nutrient critical for brain development and function. Most people may be lacking in choline. 39, 84, 85 Eggs are high in lutein and zeaxanthin, antioxidants that reduce your risk of eye disorders like macular degeneration and cataracts. 11, 15, 25, 28
  • Seafood provides the most vitamin D. Fish and seafood, especially cold-water oily fish such as salmon, herring, mackerel, anchovies and sardines, are the most valuable source of long chain omega-3 polyunsaturated fatty acids.

Studies have shown the benefits of omega-3 fatty acids in protecting against cardiovascular disease, dyslipidaemia (abnormal level of lipids in the blood including triglycerides, cholesterol), atherosclerosis, diabetes, insulin resistance, obesity, inflammation and inflammatory diseases, neurological, and neuropsychiatric disorders, osteoporosis, eye diseases. 3, 5, 6, 9, 13, 18, 21, 28, 36, 43, 44, 45, 46, 48, 68, 69, 74, 77, 78, 82, 83, 86

Aim for at least two servings of fish per week, including at least one portion of oily fish. Oily fish includes salmon, fresh tuna, sardines, mackerel and kippers.55, 56

A variety of plants provide significant protein. According to the American Dietetic Association “plant protein can meet protein requirements when a variety of plant foods is consumed and energy needs are met.” 81

  • Nuts and seeds are good source of protein, as well as fatty acids and a range of minerals, vitamins and phytochemicals, but their concentrated energy and fat content have to be taken into account when consuming.
  • Legumes including all types of beans, lentils, chickpeas, split peas, and soy products. Aside from protein, they are rich sources of carbohydrates, beta-carotene, vitamin C, folate, and dietary fiber. Consumption of a variety of legumes can play a role in prevention of a number of health conditions. A comprehensive review, that analyzes the results of 17 studies found that the risk of all-cause mortality decreased by 16% with increased intake of legumes up to 150 grams per day. 61

The amount consumed from this group depend on our daily protein requirements.

QUICK HELP: The current Recommended Dietary Allowance (RDA) for protein is 0,8 g/kg/day 37

For a woman of about 50 kg, the RDA works out to about 40-42 grams of protein per day, while a man of 70 kg would need about 56-58 grams.

Higher protein diets (up to 1,2-1,6 grams per bodyweight kilograms per day), including ~30 grams of protein per eating occasion, may support appetite control, increase satiety, reduce food cravings, and may help weight management.88

High intensity sport activities may also increase protein needs, for athletes and highly active exercising individuals 1,4 to 2,0 g/kg/day might be recommended, according to the position stand of International Society of Sport Nutrition.87

BOTTOM LINE: According to your individual protein needs, select a variety of protein foods, including at least 2 servings of seafood per week. Eat no more than 70 grams of processed meat and processed poultry a day, and no more than 450 grams of red meat per week.

SPECIAL NOTE FOR EGG CONSUMPTION: Studies concluded that regular consumption of eggs, up to 6 per week may not be associated with increased risk of heart disease, myocardial infarction or stroke in healthy individuals. 7 or more eggs per week, however, may be associated with a modest increased risk of total mortality, especially among diabetic patients, where frequent egg consumers (1 or more egg daily) are 69% more likely to have cardiovascular disease.16, 41, 59, 63

SPECIAL NOTE FOR RED MEAT CONSUMPTION: There is a lot of debate about whether it is healthy to consume red meat. EPIC (European Prospective Investigation into Cancer and Nutrition) shows a slight J-shaped positive association between red meat consumption and all-cause mortality. The lowest risk was among individuals with low to moderate consumption. 58, 61 According to the Australian Guide to Healthy Eating, consumption of no more than 450 grams per week of lean red meat may be recommended, as regular consumption of greater amounts may be associated with an increased risk of colorectal cancer. 50

SPECIAL NOTE FOR PROCESSED MEAT CONSUMPTION: The protein group includes processed meats and processed poultry, such as sausages, bacon, cured meats or reformed meat products. Processed meats are generally high in sodium and saturated fats, and intake of these products is acceptable as long as sodium, saturated fats, and total calories are within limits in the whole diet. It is recommended that no more than 70 grams of processed meat/poultry be consumed per day. A comprehensive review, that combines the results of 7 individual studies found that the risk of all-cause mortality increased by 60% with increasing intake of processed meat up to 200 grams per day. 61

QUICK HELP: for the protein content of several protein rich sources. On average:

1 serving (raw weight 100 grams) of lean meat contains about 20-25 grams of protein

1 serving (raw weight 100 grams) poultry contains about 22-25 grams of protein

1 serving (raw weight 115-120 grams) of fish contains about 20-25 grams of protein

1 chicken egg contains about 6 grams of protein

1 cup (240 ml) of yogurt or 1 cup (240 ml) of milk contains about 8 grams of protein

100 grams of medium, and semi-hard cheese contains about 22-25 grams

1 cup (225 grams) cottage cheese contain about 25-27 grams

1 cup (250 grams) of soybeans, green, raw supplies about 25 grams of protein

1 cup of raw beans (150 grams) contains about 30 grams of protein

1/2 cup of raw lentils, chickpeas, split peas (100 grams) contains about 16-22 grams of protein

Cereals, grains, nuts, and vegetables contain about 2 grams of protein per serving. 37



Food guides of health authorities and organizations usually incorporate both the written food advice and a graphic model, e.g. a pyramid, plate or rainbow, developed to communicate the key healthy eating messages. Some examples are listed below.




Dietary Guidelines for Americans with MyPlate offer ideas and tips to help you create a healthier eating style. MyPlate is a USDA symbol for making healthy choices across the food groups.70



The Australian Guide to Healthy Eating (AGTHE) is a food selection guide and the primary tool in the Eat for Health Program. It converts science for optimal health and wellbeing into a practical guide for daily recommendations of the Five Food Groups. 50



Healthy eating recommendations are visually depicted in the Eatwell Guide by Public Health England. It shows the proportion of different food types needed for a well-balanced and healthy diet. 55, 56


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