(2) What are the consequences of an unbalanced unhealthy inadequate diet?

• Overeating of energy rich foods leads to obesity and ensuing health problems (see section on obesity)

• Receiving insufficient food can cause starvation or malnutrition.

• A person is malnourished if their diet is not balanced.

• Lack of a good healthy diet can cause a person to be overweight or underweight.

• An unbalanced diet may also lead to deficiency diseases or conditions such as Type 2 diabetes.

• You need to eat the right types of healthy food and in the right amounts/proportions to maintain a healthy body.

• Starvation is when people do not get enough food to eat.

  • The effects of starvation include slow growth (particularly of young children) and a greatly increased risk of infections and irregular periods in women.

• Malnutrition: People who live on a poorly balanced diet are malnourished and malnourishment is common in the poorer developing countries of the world e.g. in Africa. What you then get are deficiency diseases.

  • Don't confuse malnutrition with starvation, where there is not enough food of any description to maintain life - the pictures you see on your TV of very thin people in Africa, on the edge of life exemplifies this pitiful state.

  • However, malnourished people can be overweight as well as thin, from an imbalanced diet e.g. those fat people who live off too much junk food and excess fat are as malnourished in some ways just as much as a 'thin' person in a poor third world country!

  • The effects of malnutrition do depend on what is missing from the diet but common symptoms are slow growth in children (arrested development), weight loss in adults, poor resistance to disease and infection, fatigue (low physical activity, lack of energy).

  • Particular deficiency diseases are caused by lack of specific vitamins or minerals e.g. lack of vitamin C causes scurvy which leads to problems with gums, skin and joints. Organ and other tissue is not efficiently repaired and ulceration is common.

  • Lack of iron can lead to anaemia, lack of oxygenated haemoglobin in the blood - you become weak and lacking in energy as respiration is less efficient.

  • Not getting enough protein in your diet causes kwashiorkor, an illness caused by severe protein deficiency, often seen in people of developing countries e.g. in Africa.

  • Lack of calcium in a diet affects bones, which become soft and poorly developed in young children. Calcium based minerals are an important component in the structure of the teeth and skeleton.

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Key points Source of information is based on textbooks & syllabus-specifications for students taking the AQA GCSE, Edexcel GCSE and OCR GCSE level biology examinations (~US grades 9-10).

Key points and more examples on the consequences of a poor inadequate diet

Consequences of an Unbalanced, Unhealthy, or Inadequate Diet

Understanding the effects of poor nutrition is essential.

A diet lacking in balance can lead to malnutrition, which includes both undernutrition (not enough nutrients) and overnutrition (too much of certain nutrients).

These imbalances can cause a range of physical and mental health problems.

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1. What Is an Unbalanced Diet?

An unbalanced diet may:

• Lack essential nutrients (e.g. vitamins, minerals, fibre)

• Contain too much sugar, salt, or saturated fat

• Provide too few or too many calories

This can result in deficiency diseases, obesity, or chronic health conditions.

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2. Diseases and Conditions Caused by Poor Diet

Condition	Cause	Symptoms/Effects
Obesity	Excess calories, especially from fats and sugars	Increased risk of heart disease, type 2 diabetes, joint pain, low self-esteem
Type 2 Diabetes	High sugar intake and obesity	High blood sugar, fatigue, blurred vision, kidney damage
Coronary Heart Disease (CHD)	High saturated fat intake → high cholesterol	Narrowed arteries, chest pain (angina), heart attacks
Constipation	Low fibre intake	Difficulty passing stools, abdominal discomfort
Scurvy	Vitamin C deficiency	Bleeding gums, poor wound healing, fatigue
Rickets	Vitamin D or calcium deficiency (common in children)	Soft, weak bones, bowed legs
Anaemia	Iron deficiency	Tiredness, pale skin, shortness of breath
Kwashiorkor	Protein deficiency (mainly in developing countries)	Swollen belly, stunted growth, muscle wasting

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3. Importance in Understanding Human Biology

Studying the consequences of poor diet helps students:

• Understand how nutrients support body systems

• Learn how imbalances affect health and development

• Explore the links between lifestyle and disease

• Appreciate the role of preventative healthcare and public health campaigns

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4. Exam Tips

• Be able to identify symptoms of deficiency diseases

• Explain how specific nutrients affect health

• Use data interpretation to evaluate diets or food labels

• Understand the long-term effects of poor nutrition

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Summary of learning objectives and key words or phrases about the consequences of an unbalanced - unhealthy diet and the diseases it can cause

Know what is meant by an unbalanced- unhealthy diet and what it lacks.

Know what is meant by malnutrition and starvation and their consequences.

Know that the consequences of an unbalanced unhealthy inadequate diet can be serious e.g. lack of iron causing anaemia/anemia, lack of protein causing the disease kwashiorkor and lack of calcium affecting teeth and bone growth.

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