Basic concepts

Essential fatty acids are fatty acids that the human body cannot synthesise in sufficient amounts, so they must come from food. They contribute to cell membranes, growth, nervous-system functions and the production of signalling substances. Their essential status refers to the need for dietary supply, not to the idea that every dietary fat is harmful or beneficial.

Vitamins A, D, E and K are fat-soluble. Dietary fat, together with normal bile and digestive processes, helps dissolve and absorb them in the intestine. Extremely low-fat diets or disorders affecting bile, pancreatic function or intestinal absorption may reduce their uptake. This does not mean excessive fat is required; a suitable amount is sufficient.

Vitamin C is required for collagen synthesis, which supports skin, connective tissue, blood vessels and wound healing. It also improves the absorption of non-haem iron from plant foods, especially when eaten in the same meal. Citrus fruits, guava, amla and several vegetables are useful sources. It does not colour food or produce sodium.

Folate, or vitamin B9, is involved in DNA synthesis and the production of new cells, including red blood cells. Adequate folate is especially important before conception and during pregnancy because it supports rapid cell division and helps reduce the risk of neural-tube defects. Deficiency may contribute to megaloblastic anaemia.

Potassium is an important intracellular electrolyte. Along with sodium and other ions, it helps maintain fluid and acid-base balance and creates electrical gradients needed for nerve transmission and muscle contraction, including normal heart rhythm. Its function is physiological and regulatory, not related to food colour, fat formation or preventing sleep.

Antioxidant nutrients help limit damage caused by reactive oxygen species and other free radicals, which can affect cell membranes, proteins and DNA. Important dietary examples include vitamin C, vitamin E and carotenoids such as beta-carotene. Antioxidants support protection but do not make a person immune to disease or replace a balanced diet and medical care.

Cooking changes food structure and can have different effects on different nutrients. Heat and water may reduce some heat-sensitive or water-soluble vitamins, especially with prolonged boiling and discarded water, while cooking can improve digestibility and increase the availability of some nutrients. Using suitable time, temperature and limited water helps conserve nutritional value.

During sprouting, metabolic activity begins in the seed. This can increase the content or availability of some vitamins, reduce certain antinutritional factors and make pulses easier to digest. Sprouting does not remove all protein; rather, it may improve the usable nutritional quality of the food when hygienic conditions and proper storage are maintained.

Fermentation uses beneficial microorganisms to transform food components. It may partially break down complex carbohydrates or proteins, improve flavour and digestibility, and increase the availability of some nutrients. Examples include curd and traditionally fermented batters such as idli. The result depends on the food, microorganisms, time, temperature and hygiene of preparation.

Nutrition information becomes useful only when it leads to suitable action. Behaviour change helps a person convert advice into regular practices, such as eating a balanced diet, reducing excess sugar or salt, and following appropriate meal timings. Gradual, realistic goals are easier to maintain and can improve health over a long period.

Clinical diets are planned by applying normal nutrition principles to a person’s disease, symptoms, nutritional status and treatment needs. Knowledge of nutrients, energy, digestion and balanced meals helps a professional decide what should be increased, reduced, restricted or modified. It supports diet therapy but does not replace prescribed medicines.

Small practical goals reduce the difficulty of changing established eating habits. A person may begin by adding one fruit, drinking water instead of a sugary drink, or reducing salt gradually. Such goals are specific, measurable and achievable, so success builds confidence and supports lasting behaviour change.

BMI is calculated from weight and height and is useful for screening groups, but it cannot distinguish muscle from fat or show where fat is stored. A muscular person may have a high BMI without excess fat, while abdominal fat may be missed; waist measurement and clinical assessment add useful information.

Waist circumference gives an indication of central or abdominal fat accumulation. Excess abdominal fat is associated with greater risk of insulin resistance, type 2 diabetes, high blood pressure, and cardiovascular disease. It is a screening measure, not a complete diagnosis, and should be interpreted with other health information.

People may forget snacks, portion sizes, cooking fats, beverages, or foods eaten outside the home. Repeating or rephrasing questions and asking for concrete examples can improve recall and reveal discrepancies. The interviewer should remain respectful so that the information becomes more accurate rather than making the patient uncomfortable.

In a twenty-four-hour recall, the respondent reports all foods and drinks consumed during the preceding day or twenty-four-hour period. The interviewer probes timing, ingredients, portion sizes, preparation, and snacks. It gives useful intake information, although one day may not represent the person’s usual pattern.

A food diary records foods and drinks close to the time they are consumed, often across several days. It can show meal timing, portions, repeated choices, skipped meals, snacks, and beverage patterns more directly than memory alone. Accurate recording still requires cooperation and may sometimes change usual behaviour.

Nutrition myths may encourage people to avoid essential foods, use unsafe supplements, follow unbalanced diets, or delay professional care. Because myths are often repeated confidently, they can appear credible without evidence. Reliable nutrition advice should be based on scientific research, individual needs, and guidance from qualified professionals.

Energy balance compares the energy obtained from food and beverages with the energy used by the body for metabolism, movement, and physical activity. When intake is greater than expenditure over time, weight may increase; when expenditure is greater, weight may decrease. Thus it is most directly used to understand weight change.

Successful meal planning requires more than calculating nutrients. The plan must be acceptable to the person, affordable, culturally suitable, available locally, practical to prepare, and compatible with the person's schedule and health needs. If these factors are ignored, adherence may be poor even when the nutrient calculations are scientifically correct.

Body weight is only one indicator of nutritional status. A person may have normal weight but still suffer from iron, iodine, vitamin A, vitamin D, or other micronutrient deficiencies. Proper assessment also considers height, growth pattern, diet history, clinical signs, biochemical tests, and health context; therefore option A is correct.

Undernutrition develops when the body receives insufficient energy, protein, or other essential nutrients for an extended period. Long-term low intake can impair growth, immunity, muscle maintenance, work capacity, and recovery from illness. Excess fried food suggests another concern, while a varied balanced diet and safe water do not indicate undernutrition.

Overnutrition occurs when energy or particular nutrients are consumed in excess of the body's needs, especially over a prolonged period. Persistent excess energy can contribute to weight gain, obesity, and related non-communicable diseases. The other options describe inadequate intake or deficiency, which are associated with undernutrition rather than overnutrition.

Raw foods, especially raw meat, poultry, eggs, and seafood, may carry harmful microorganisms. If their juices, utensils, hands, or cutting boards contact cooked or ready-to-eat food, those organisms can transfer through cross-contamination. Separating foods, using clean equipment, and washing hands helps prevent foodborne illness.

Considering culture, religion, customary foods, family routines and available cooking practices can make a meal plan acceptable and realistic. When people recognize familiar foods and preparation methods, they are more likely to follow the plan consistently. This improves dietary compliance, provided that nutritional adequacy, hygiene and individual medical needs are also respected.