Macronutrients
Chuong Pham-Huy, Bruno Pham Huy in Food and Lifestyle in Health and Disease, 2022
Macronutrients are nutrients that the body needs in large amounts for the production of energy for body activity. There are three classes of macronutrients: carbohydrates (sugars), proteins and lipids (fats). They can be metabolically processed into cellular energy. Water is also an essential nutrient required in a large amount, but unlike the other macronutrients, it does not yield energy. The energy from macronutrients comes from their chemical bonds (1). This chemical energy is converted into cellular energy that is then utilized to perform work, allowing our bodies to conduct their basic functions such as movement, respiration, excretion, growth and reproduction (1). A unit of measurement of food energy is the calorie. Both carbohydrates and proteins provide 4 kcal/gram, and lipids provide 9 kcal/gram for humans (3).
Lifestyle Approaches Targeting Obesity to Reduce Cancer Risk, Progression, and Recurrence
James M. Rippe in Lifestyle Medicine, 2019
A major contributor to the obesity epidemic is the availability and appeal of energy-dense foods, which are defined as having an energy content of at least 225 Kcal per 100 grams. The densest micronutrient is fat, as each gram of fat equals nine calories. Each gram of protein or carbohydrate, on the other hand, corresponds to four calories.99 Naturally, for the same number of calories, a person can consume a much larger portion of food with lower energy density than a food higher in energy density. As an example, one orange has 1/4 of the energy density of one fried egg. In general, foods with the lowest energy density tend to be high in water and fiber content and very low in fat (fruits and vegetables). The consumption of energy-dense foods should be done sparingly.100 Sugary drinks should be avoided completely and so should fast foods. Fruit juices should also be limited. Fruits are best eaten whole.100
General Nutrition
Maria A. Fiatarone Singh, John Sutton Chair in Exercise, Nutrition, and the Older Woman, 2000
Nutrition is more than just the food we choose to eat. The science of nutrition encompasses all the interactions that occur between living organisms and the nutrients in food. These include the body’s ingestion, digestion, absorption, transport, metabolism, storage, and excretion of nutrients. Nutrients are chemical substances that provide energy, structure, and regulation of body processes. To date, approximately 45 nutrients must be supplied by the diet and are known as essential for human life. The six classes of nutrients are carbohydrate, fat, protein, vitamins, minerals, and water. When food is metabolized in the body, carbohydrate, fat, and protein are broken down to yield energy, measured in calories, which supports all of the activities we perform. The carbohydrate and protein in food supply 4 calories per gram, and fat supplies 9 calories per gram. The vitamins, minerals, and water do not provide energy, but help in metabolic, structural, and regulatory processes in the body.
Should fast-food nutritional labelling in South Africa be mandatory?
Published in South African Journal of Clinical Nutrition, 2022
Siphiwe N Dlamini, Gudani Mukoma, Shane A Norris
The United States government was the first to mandate restaurants to provide nutritional labelling of their products, which became effective from May 2018. Their regulations require labelling the energy content (as calories) of standard food items that are listed on menus and menu boards, for restaurants with 20 or more outlets that operate under the same name and provide the same menu items.14 The restaurants are also obligated to have information such as total fat, saturated fat, trans fat, cholesterol, sodium, total carbohydrates, dietary fibre, sugars and protein content available on the premises upon consumer request. In support of the effectiveness of fast-food labelling in the fight against obesity, recent evidence suggested that United States restaurants have already started reducing the energy content of their food products in response to these regulations.13 Similarly, the United Kingdom government has recently announced that restaurants in England with 250 or more employees will be required to display energy contents of their non-prepacked foods from April 2022.17
Optimal Protein Intake during Weight Loss Interventions in Older Adults with Obesity
Published in Journal of Nutrition in Gerontology and Geriatrics, 2019
When ≥20% of total calories come from protein, the standard RDA of 0.8 g/kg/day will be exceeded, unless total daily caloric intake falls below 1000 kcal. If energy intake chronically falls below this level, nutritional adequacy suffers (25). Several studies supplied at least 20% of calories from protein (35, 38, 39, 58–62), but only one study described an intervention below 1000 kcal, sustained for a limited period of 3 months (36). Research is pointing to the importance of protein adequacy not only as a total daily intake, but also from meal to meal, with a goal of at least 20–30 g per meal (68). Several studies balanced protein in this manner with beneficial results on muscle and function (58, 59, 63). As others have pointed out, 30 g of protein per meal (≥90 g protein daily) appears to indicate that the current RDA is inadequate (69). The RDA would be further exceeded with the addition of a protein-rich snack or supplement after exercise or prior to bedtime (39, 63).
Factors influencing dietary fat intake among black emerging adults
Published in Journal of American College Health, 2018
Shalonda E. B. Horton, Gayle M. Timmerman, Adama Brown
There were no statistically significant differences in the outcome variable based on the type of survey type (paper and online). According to the Blocker Dietary Fat Screener categories,45 the sample's DFI mean score of 24.75 (SD = 10.65) is considered very high fat intake. Approximately 40%–50% of one's calories come from fat for DFI scores ≥ 23.45 About 59% of the sample's DFI scores were categorized as very high fat intake with their percent of daily calories from fat ranging from 25% to 53% (M = 36.38, SD = 6.22). Their total dietary fat, saturated fat, and cholesterol ranged 51.90 to 167.34 g (M = 100.58, SD = 24.83), 9.42 to 58.77 g (M = 28.40, SD = 9.71), and 133.15 to 594.18 mg (M = 306.71, SD = 90.03), respectively. The difference between mean DFI scores for males and females (5.61) was significant (t [75.553] = 3.125, p = .003), with more males (69%) categorized as very high fat intake compared to females (56%). Additionally, males had statistically significant higher intakes of saturated fat (35 g versus 27 g, t[233] = 5.166, p = .000) and dietary cholesterol (381 mg versus 285 mg, t[233] = 6.866, p = .000), respectively, compared to females.