A Healthy Diet
At recess, Ximena buys a bag of potato chips and a soda; Diego buys a torta (a sandwich) with avocado and a glass of hibiscus water. Both feel full, but do they give their bodies the same thing? During adolescence you grow at top speed, and what you eat today shows up in your bones, your muscles, and your brain a few years from now.
Foods and nutrients
A plate of pot beans looks like just seeds in broth. But when you digest it, your body gets iron for the blood, protein for the muscles, and starch for energy. How is what you put in your mouth different from the substances your cells actually use?
Nutrients are also divided into essential (the body does not make them, or not in sufficient amounts, so you must get them from your diet: vitamins, certain amino acids and fatty acids, mineral salts such as iron or calcium) and non-essential (the body can make them from other substances, such as some amino acids and cholesterol). "Non-essential" does not mean "useless": it means your body can produce it if it gets the raw materials.
Name the groups of nutrients that a complete diet must include (proteins, carbohydrates, lipids, vitamins, mineral salts and water) and state a general function of each…
Name the groups of nutrients that a complete diet must include (proteins, carbohydrates, lipids, vitamins, mineral salts and water) and state a general function of each group in the body.
A supplement company promotes snack bars claiming they contain "$100\ \%$ of the non-essential nutrients your body needs", and asserts that thanks to this "it is no…
A supplement company promotes snack bars claiming they contain "$100\ \%$ of the non-essential nutrients your body needs", and asserts that thanks to this "it is no longer necessary to worry about eating fruit, vegetables, or legumes".\na) Scientifically refute this advertisement by explaining the difference between an essential and a non-essential nutrient, and give two examples of each group.\nb) Predict what biological consequences a person who based their diet solely on these bars would suffer, and justify why no single food—no matter how complete it is advertised to be—can replace a varied diet.
The Plato del Bien Comer (Healthy Plate)
So that you don't have to calculate nutrients at every meal, in Mexico we use the Plato del Bien Comer (the "Healthy Plate"), a nutrition guide that sorts foods into three groups and shows that they should be combined at every meal.
How to read the proportions
In any guide shaped like a plate or a wheel, the size of the section shows how much of your daily diet that group should make up: the biggest section is the one that should dominate; the smaller ones, or those left out of the plate, are for occasional consumption. As a general guideline, vegetables and fruits take up about half of what you eat, and cereals and legumes with animal-source foods share the rest. Sweets, sodas, snack chips, packaged sweet bread, and fried foods are not part of the plate: they are for occasional consumption.
The food wheel shows several food groups labelled with letters, with larger sectors indicating a greater presence required in the daily diet. State which letter occupies…
The food wheel shows several food groups labelled with letters, with larger sectors indicating a greater presence required in the daily diet. State which letter occupies the sector that should dominate our diet, which food group it corresponds to, and which letter indicates the group whose consumption should be occasional.
The Mediterranean diet as a model
Scientists have studied what populations with less heart and blood disease eat. One of the most studied diets is the Mediterranean diet, typical of countries in southern Europe. It is based on varied, seasonal plant foods, olive oil as the main fat, and little red meat and few sweets.
| Frequency | Foods |
|---|---|
| Every day | Vegetables, fruits, cereals (preferably whole grain), legumes, nuts, olive oil, dairy such as yogurt or cheese, water |
| A few times a week | Fish, eggs, poultry |
| Occasionally (a few times a month) | Red meat, cured meats, sweets and pastries |
Now compare it with what many teenagers eat: soda and packaged juices almost daily, snack chips and packaged sweet bread, fast food several times a week, and few vegetables, fruits, and legumes. In other words, exactly the opposite: what should be occasional becomes daily, and what should be daily is eaten rarely.
The Mediterranean diet is considered a healthy model. Describe its main characteristics (predominant foods, primary fat source, consumption frequency for each group) and…
The Mediterranean diet is considered a healthy model. Describe its main characteristics (predominant foods, primary fat source, consumption frequency for each group) and compare it with the typical diet of many teenagers today.
Organizing the day's meals
Eating well is not only about what you eat, but also about how you spread it out. The ideal is three main meals and light snacks (colaciones), such as fruit, vegetables, or peanuts, with variety, regularity, and water as your usual drink.
Breakfast is important because you arrive after hours of fasting: it provides the energy and nutrients for attention and good performance in class. A balanced breakfast combines several groups: for example, eggs with beans (proteins), a tortilla or whole-grain bread (carbohydrates and fiber), fruit (vitamins and fiber), and milk or water.
Explain why breakfast is considered an important meal, especially for school-age children, and describe a balanced breakfast indicating which nutrients are provided by…
Explain why breakfast is considered an important meal, especially for school-age children, and describe a balanced breakfast indicating which nutrients are provided by each food item you include.
A 14-year-old female athlete needs about $2200\ \text{kcal}$ per day. If her breakfast provides about $450\ \text{kcal}$, calculate what percentage of her daily energy…
A 14-year-old female athlete needs about $2200\ \text{kcal}$ per day. If her breakfast provides about $450\ \text{kcal}$, calculate what percentage of her daily energy intake is covered by breakfast and reason whether it complies with the recommendation that breakfast should provide around $25\ \%$ of daily calories.
Ultra-processed foods, warning labels, and nutrition labels
Ultra-processed foods (sodas, packaged sweet bread, snack chips, cookies, candy, instant soups) are made with lots of sugar, salt, fats, and additives, and provide a lot of energy with few nutrients. "Processed" is not always bad: canned beans or pasteurized milk can be part of a balanced diet. The problem is an excess of sugars, salt, and saturated fats.
To help you decide, Mexican packages carry black warning labels (sellos de advertencia) with the words "EXCESO CALORÍAS" (excess calories), "EXCESO AZÚCARES" (excess sugars), "EXCESO GRASAS SATURADAS" (excess saturated fats), "EXCESO GRASAS TRANS" (excess trans fats), or "EXCESO SODIO" (excess sodium). If a product has several labels, it is best to keep it as an occasional food.
Risk factors can be reduced with protective factors: eating vegetables and fruits, drinking plain water instead of soda, cooking at home, being active at least 60 minutes a day, and reading labels. Choosing them is part of your healthy life plan.
Analyse this one-day menu: breakfast, a pre-packaged pastry and a soft drink; lunch, a burger with chips and a soft drink; dinner, pizza. Point out what problems it…
Analyse this one-day menu: breakfast, a pre-packaged pastry and a soft drink; lunch, a burger with chips and a soft drink; dinner, pizza. Point out what problems it presents from the perspective of a balanced diet and suggest three specific changes to improve it.
The nutrition label on a package of cookies indicates that every $100\ \text{g}$ contains $20\ \text{g}$ of fat, $65\ \text{g}$ of carbohydrates (of which $30\ \text{g}$…
The nutrition label on a package of cookies indicates that every $100\ \text{g}$ contains $20\ \text{g}$ of fat, $65\ \text{g}$ of carbohydrates (of which $30\ \text{g}$ are sugars) and $6\ \text{g}$ of protein. The WHO recommends that free sugars should not exceed $10\ \%$ of daily energy. Knowing that $1\ \text{g}$ of sugar provides about $4\ \text{kcal}$ and that a teenager consumes about $2200\ \text{kcal}$ per day, calculate how many grams of these cookies would reach that limit if they were the only source of sugar for the day, and comment on the result.
When eating becomes a problem
Some people live in fear of food. Eating disorders, such as anorexia and bulimia, are physical and mental health illnesses, not "lack of willpower" or whims. They often begin in adolescence and are linked to pressures about the body and image.
| Anorexia | Bulimia | |
|---|---|---|
| Behavior | Severely restricts food, counts calories, avoids eating with others | Binge eating followed by vomiting, laxatives, or excessive exercise |
| Weight | Striking weight loss | May stay normal, which makes it hard to notice |
| Emotions | Intense fear of gaining weight, distorted body image | Guilt and shame |
Imagine that you observe the following changes in a $14$-year-old classmate: they systematically skip recess snack saying they already ate at home, show constant worry…
Imagine that you observe the following changes in a $14$-year-old classmate: they systematically skip recess snack saying they already ate at home, show constant worry about the calories in any food, have noticeably lost weight, and when the group suggests eating pizza, react with distress and isolate themselves.\na) Interpret these signs and deduce what type of eating disorder (ED) could be developing, comparing its main characteristics with those of bulimia.\nb) A friend suggests: "Let's not say anything to anyone; it's just a lack of willpower, it will pass". Refute their stance using biological and psychological arguments, and design a responsible action plan to seek immediate professional help from the school environment.
Back to the beginning: Ximena and Diego do not give their bodies the same thing. The torta with beans, vegetables, and avocado provides varied nutrients; the chips and the soda provide mostly energy, salt, and sugar. Choosing well at recess is a small decision that supports your future health.