Unintentional weight loss is a noticeable drop in body weight that occurs even if the person is not trying to lose weight. It can be a symptom of a serious illness. Any unintentional weight loss of less than 5 percent of body weight (or 10 pounds) may be a sign of serious conditions, such as Thyroid problems, Cancer, Infectious diseases, Digestive diseases, Certain medicines, etc.
On other hand, unintentional weight gain is much more common, and happens when you increase the amount of food intake or decrease the amount of exercises. It may also be caused by excess fluid in the body, abnormal growths, constipation, pregnancy or hormonal causes, such as hypothyroidism(low thyroid hormone levels).
Unintentional weight gain can be periodic, continuous, or rapid. One example of unintentional weight gain is experienced during a woman’s menstrual cycle. Whereas, rapid unintentional weight gain may be due to medication side effects, especially if it is new medications.
Overweight is abnormal weight gain that can cause severe risks to health, such as High Blood Pressure, Type 2 diabetes, Stroke, Heart diseases, Sleep Apnoea (sleep disorder in which breathing stops and starts), Osteoarthritis, Atherosclerosis(formation of plaque in the blood vessels), Kidney failure, Liver failure, and Obesity.
Whereas, being underweight is having a body weight too low to be healthy. Severe forms of underweight could cause weakened immune systems, fragile bones and feeling tired. When you lose weight, it’s not just fat that you lose, but also the muscles. Weaker muscles mean inconvenience in performing day-to-day activities.
As you grow older, if you continue eating the same types and amounts of food without being more active, you will probably gain weight. That’s because your metabolism (the rate our body obtains energy from our food intake) can slow with age. It’s important to choose nutrient-dense foods and be active at least 150 minutes per week.
As a rule of thumb: