2.2 Diet · ThinkerQAQ

This is a historical learning note and may contain outdated or incomplete understanding.

1. What Is a Healthy Diet?

Energy balance + nutrient balance

2. Nutrient Balance

Food contains seven major nutrients.

2.1. Protein Balance

2.1.1. Protein Intake

Animal protein + plant protein

2.1.2. Protein Consumption

The human brain, nerves, skin, muscles, internal organs, blood, and even nails and hair are mainly composed of protein. Protein is also a repair material used for growth and development, renewal of aging tissues, and formation of new cells in damaged tissues.
If energy is insufficient and the body’s carbohydrates have been used up, the body supplies energy by consuming fat and protein.

2.1.3. Protein Balance

Animal protein should account for half of total protein.

2.1.4. Signs of Protein Imbalance

Too little intake
- Frequent colds, delayed development, anemia, fatigue, etc.
Too much intake
- Gastrointestinal dysfunction. When protein intake is too high and exceeds the digestive capacity of the gastrointestinal tract, gastrointestinal dysfunction can occur.
- Liver damage. When protein intake is excessive, too much toxic gas accumulates in the intestine. These gases are absorbed into the blood and eventually reach the liver for detoxification. Therefore, if protein intake is too high and exceeds the liver’s detoxification capacity, liver damage can occur.
- Kidney damage. Protein metabolites that cannot be used by the body, such as urea, creatinine, creatine, and uric acid, need to be filtered by the kidneys into the urine and then excreted. If the amount of metabolic waste is large, kidney filtration increases, increasing the burden on the kidneys and causing kidney damage.

2.2. Carbohydrate Balance

2.2.1. Carbohydrate Intake

Staple foods such as grains, tubers, mixed grains, and legumes.

2.2.2. Carbohydrate Consumption

Provides energy.

2.2.3. Carbohydrate Balance

Eat at least 150 g of grain foods every day.

2.2.4. Signs of Carbohydrate Imbalance

Too much intake
- Abnormal blood glucose and abdominal obesity.

2.3. Fat Balance

2.3.1. Fat Intake

Meat, eggs, dairy, fish, vegetable oils, nuts, etc.

2.3.2. Fat Consumption

Provides calories, supplies essential fatty acids, protects internal organs, etc.

2.3.3. Fat Balance

Animal fat should account for half and plant fat should account for half.

2.3.4. Signs of Fat Imbalance

Obesity, brain atrophy, infertility.

2.4. Vitamin Balance

There are two types of vitamins: fat-soluble and water-soluble. With water-soluble vitamins, the concern is not excessive intake but insufficient intake; excessive intake of fat-soluble vitamins can cause toxicity.

2.4.1. Vitamin A

2.4.1.1. Vitamin A Intake

Obtain vitamin A directly from animal liver, butter, and eggs.
Create an oily environment to dissolve carotene from plants, for example by eating beef brisket stewed with carrots, pork stewed with pumpkin, stir-fried broccoli, stir-fried bok choy, or stir-fried spinach.

2.4.1.2. Signs of Vitamin A Deficiency

Night blindness, xerophthalmia, chronic pharyngitis.

2.4.2. Vitamin D

2.4.2.1. Vitamin D Intake

Obtain it directly from animal foods. Foods containing vitamin D include animal liver, brain, lungs, spleen, eggs, milk, salmon, chum salmon, and small amounts in animal bones and skin.
Synthesis in human skin. The epidermis and dermis contain a certain amount of 7-dehydrocholesterol. When exposed to sunlight or ultraviolet light, it can form previtamin D3 through a photochemical reaction, then undergo hydroxylation in the liver and kidneys, and finally be converted into active vitamin D3. Our ancestors were not deficient in vitamin D because their diets contained plenty of meat, and they also received enough sunlight while hunting outdoors.

2.4.2.2. Signs of Vitamin D Deficiency

Osteoporosis, hypertension, depression.

2.4.3. Vitamin B

2.4.3.1. Vitamin B Intake

Vitamin B1 — seed coats, animal organs, and lean meat.
Vitamin B2 — animal liver, dairy products, eggs, legumes, and leafy green vegetables.
Vitamin B6 — animal liver, dairy products, eggs, legumes, leafy green vegetables, and whole-grain foods.
Vitamin B12 — animal liver, meat, eggs, and dairy products.
Folate — animal liver, kidneys, eggs, legumes, leafy green vegetables, fruit, and nuts.

2.4.3.2. Signs of Vitamin B Deficiency

Symptoms described as “internal heat,” reduced memory, indigestion.

2.5. Mineral Balance

2.5.1. Calcium

2.5.1.1. Calcium Intake

Milk and dairy products.

2.5.1.2. Signs of Calcium Deficiency

Leg cramps, asthma, high blood pressure, etc.

2.5.2. Magnesium

2.5.2.1. Magnesium Intake

Fresh leafy green vegetables and seafood.

2.5.2.2. Signs of Magnesium Deficiency

Early magnesium deficiency often appears as gastrointestinal symptoms such as loss of appetite, nausea, and vomiting. As magnesium deficiency worsens, corresponding neurological symptoms can appear, such as memory decline, nervousness, excitability, confusion, restlessness, and athetosis. In severe cases, seizures and arrhythmias can occur.

2.5.3. Iron

2.5.3.1. Iron Intake

Eat animal liver, whole blood, meat, fish, and poultry.

2.5.3.2. Signs of Iron Deficiency

Anemia.

2.5.4. Zinc

2.5.4.1. Zinc Intake

Oysters contain the most, followed by animal organs, then beef, pork, and lamb. Eggs are also good. Legumes, grains, vegetables, and fruit contain relatively little zinc.

2.5.4.2. Signs of Zinc Deficiency

Delayed development and poor appetite.

2.5.5. Iodine

2.5.5.1. Iodine Intake

Seafood.

2.5.5.2. Signs of Iodine Deficiency

Goiter.

2.6. Dietary Fiber Balance

2.6.1. Dietary Fiber Intake

Fruit and vegetables.

2.6.2. Dietary Fiber Consumption

Soluble dietary fiber. It is not consumed directly by the human body; instead, intestinal bacteria eat it and convert it into energy for the bacteria, which helps normal gut flora reproduce.
Insoluble dietary fiber. It is not easily fermented by bacteria and includes cellulose, hemicellulose, lignin, resistant starch, etc. It is mainly found in coarse grains, the outer coats of legume seeds, and plant stems and leaves.

2.6.3. Dietary Fiber Balance

2.6.4. Signs of Dietary Fiber Imbalance

Obesity, high blood glucose, constipation, malnutrition.

2.7. Water Balance

2.7.1. Water Intake

A person’s total daily water intake is about 2500 mL, from drinking water, food, and metabolism.

2.7.2. Water Consumption

A person’s total daily water output is also about 2500 mL, through the kidneys, breathing, skin, and stool.

2.7.3. Water Balance

One method is to see whether you feel thirsty. Waiting until you are thirsty before drinking water is not right. With an appropriate water intake, a person should not feel thirsty.
Another method is to observe urine color and urine volume. Normally, urine is pale yellow and daily urine output is about 1500 mL, usually with urination every three to four hours. If you do not feel the need to urinate for half a day, or your urine is dark yellow, that indicates insufficient water intake. Conversely, if you urinate frequently and the urine is as clear as water, you may be drinking too much.

3. Energy Balance

3.1. Energy Intake

Three of the seven major nutrients can provide energy.

3.1.1. Carbohydrates

Each gram of carbohydrate provides 4 kilocalories of energy.

3.1.2. Protein

Each gram of protein provides 4 kilocalories of energy.

3.1.3. Fat

Each gram of fat provides 9 kilocalories of energy.

3.2. Energy Expenditure

3.2.1. Basal Metabolism

The metabolic rate measured after excluding other influencing factors as much as possible, in a very quiet environment, while awake, with the body unaffected by mental stress, muscular activity, environmental temperature, and similar factors.

3.2.2. Exercise

Energy consumed by exercise.

3.2.3. Food Digestion

Digesting food also consumes energy. This is called the thermic effect of food.

3.3. Energy Balance

Total energy intake > energy expenditure = obesity Total energy intake < energy expenditure = thinness Total energy intake = energy expenditure = normal body weight

Standard body weight 172 - 105 = 67 kg
Total energy that needs to be expended 67 * 35 = 2345
Calculate the proportions of the three energy-yielding nutrients
- Carbohydrates: 2345 * 0.55 = 1290 KJ; 1290 / 4 = 322 g.
  - Coarse grains and refined grains each account for half, so 322 / 2 = 161 g.
  - One baozi is 50 g; one bowl of rice is 250–450 g.
- Protein: 2345 * 0.15 = 352 KJ; 352 / 4 = 88 g.
  - One egg contains 6 g.
  - One 200 mL bottle of milk contains 6 g.
  - 100 g of meat contains 17–20 g.
- Fat: 2345 * 0.3 = 703 KJ; 703 / 9 = 78 g.
  - Vegetable oil and animal fat each account for half, so 78 / 2 = 39 g.

One serving of whole grains ≈ one fist ≈ 180 g
One serving of pasta ≈ one fist ≈ 75 g
One serving of leafy vegetables ≈ one large handful ≈ 80 g
One serving of non-leafy vegetables ≈ one fist ≈ 80 g
One serving of fruit ≈ one small handful ≈ 80 g
One serving of meat ≈ one palm ≈ 100 g
One serving of fish ≈ one whole hand ≈ 150 g
One serving of oily fish ≈ one palm ≈ 100 g
One serving of nuts ≈ one cupped hand ≈ 10 g

4. Intermittent Fasting

4.1. What Is It?

Do not eat for a period of time each day or each week. It focuses on when to eat rather than what to eat.

4.2. Methods

Alternate-day fasting. Eat normally for one day, then completely fast or eat only one small meal the next day (below 500 calories).
5:2 fasting. Eat normally five days per week and fast two days per week.
16:8 fasting / daily time-restricted eating. Eat normally, but only within an eight-hour window each day. For example, skip breakfast, eat lunch around noon, and eat dinner at 8 p.m.

4.3. Benefits / Drawbacks

4.3.1. Benefits

Weight loss
Insulin resistance
Inflammation
Heart health
Cancer
Brain health
Anti-aging

4.3.2. Drawbacks

There may be side effects, but they usually disappear within a month. Side effects may include:

Hunger
Fatigue
Insomnia
Nausea
Headache