4 Reasons Why Some People Eat A Lot But Never Get Fat
Food Myths

4 Reasons Why Some People Eat A Lot But Never Get Fat

23 Mins read
cigna-teamAuthorCigna Team

It is enviable how some people can't seem to gain weight or get fat even though they eat a lot, while others constantly struggle with their weight issues despite putting a lot of effort to cut down calories and exercising.

This can be boiled down to good genes with a high metabolism, although experts say nutritional and behavioural factors could play a part to stave off the extra pounds of a person’s body weight.

It is crucial to rule out underlying medical conditions such as hyperthyroidism and celiac disease, a severe condition of intolerance towards gluten if you are constantly underweight despite consuming enough calories.

Our tendency to gain or maintain body weight is complex, genetics, nutritional and behavioural factors all play a role. The extent to which each of those factors affects our weight varies, according to the individual.

A 2019 study carried out by Cambridge researchers reveals that hundreds of genes have been found that increase the chance of a person being overweight. The researchers also found that obese people had a higher genetic risk score than normal-weight people, which contributes to their risk of being overweight. On the other hand, the result not only showed that thin people had fewer genetic variants that we know increase a person’s chances of being overweight, but they also had new genetic regions involved in healthy thinness.

The truth is, there is no genetic on-off switch that allows some people to binge-eat and defies the fundamental rules of weight gain. We might have overlooked the lifestyle behaviours and hormonal factors of those who seem never to gain fat.

  1. Only Eat When You're Physically Hungry

    Sometimes it is all in the mind. Some may have a huge appetite, consuming more than they should and end up putting on weight, which eventually may lead to obesity. Only eat when you feel physically hungry, not when you are craving for something.

  2. Hormonal factors

    Hunger is controlled by two hormones — ghrelin and leptin. Leptin, which is produced by fat cells suppresses appetite while ghrelin does the opposite to stimulate your appetite. People with higher leptin sensitivity or production find it easier to control craving or lose weight.

  3. Proper Sleep Pattern

    You can however control your hormones by getting at least seven hours of sleep a night. Sleep deprivation can send your ghrelin level spiking and the body will overproduce cortisol, a hormone that instigates hunger. In short, sleeping more could cause a person to weigh less.

  4. Healthy Eating Habits

    How you eat also determines the amount you consume. If you’re eating at a slower pace and chewing more you’re less likely to gain much weight, as your brain gets more time to signal the body that you are full.

    Experts recommend having your meals sitting down because eating standing up is usually associated with snacking and you may end up eating more than you need.

People who eat a lot but don’t get fat may look thinner on the outside, but it doesn’t mean that they are healthier. Besides, a lower weight does not necessarily associate with lower body fat. Thin people can also suffer from diseases related to obesity. Since they don’t get fat, they may be more likely to ignore the issue and hence increase the risks of related health problems.

Also, people who don’t get fat because of poor digestion preventing the absorption of nutrients may encounter health problems such as endocrine disorders, menopause of women, osteoporosis or nutritional anemia.

Yet those who are constantly skinny may want to gain some muscle mass. A diet that is high in protein with nutrient-dense foods, as well as exercising and strength training can help you to bulk up gradually.

Maximize your intake of nutritious foods by switching to healthier options such as brown rice, high-fat dairy and high-protein meats.

Some of the nutrient-dense food that can help you to gain weight healthily:

  • Nuts: Almonds, walnuts, macadamia nuts
  • Dried fruits: Raisins, dates, prunes
  • High-fat dairy: Whole milk, full-fat yoghurt
  • Fats and oils: Avocado, extra virgin olive oil
  • Grains: Rolled oats, brown rice
  • Tubers: Sweet potatoes, yams
  • Meat: Chicken, beef, pork, lamb

Besides eating nutrient-dense foods to help gain weight, here are some tips to improve the digestive system and boost nutrients absorption for people who don’t get fat because of poor digestion preventing the absorption of nutrients.

  • Consume foods containing probiotics such as yogurt and natto to improve the gut microbiome
  • Consume foods containing prebiotics such as garlic, onions, and wheat to improve gut health
  • Consume enzyme-rich fruits such as pineapple and kiwi to help food digestion
  • Avoid fried foods, artificial sweetener, alcohol and other hard-to-digest foods to prevent the bowel moves too quickly which affects nutrient absorption
  • Avoid undigested food like sticky rice to prevent the bowel moves too slowly which causes a feeling of fullness and eventually, inability to consume

Overweight and obesity are major risk factors for a number of chronic diseases, including cardiovascular diseases such as heart disease and stroke, which are the leading causes of death worldwide.

According to the World Health Organization, overweight and obesity are defined as abnormal or excessive fat accumulation that presents a risk to health. A body mass index (BMI) over 25 is considered overweight, and over 30 is obese.

Overweight and obesity are major risk factors for a number of serious diseases and health conditions, including the following:

  • High blood pressure
  • High cholesterol level
  • Type 2 diabetes
  • Coronary heart disease
  • Stroke
  • Gallbladder disease
  • Osteoarthritis
  • Sleep apnea
  • Mental illness
  • Difficulty with physical functioning

In order to reduce the risks of the above-mentioned health conditions, overweight and obese people are recommended to aim for a healthy weight by adopting lifelong healthy lifestyle changes.

Here are a few tips for maintaining a healthy weight:

  • Limit portion size to control calorie intake
  • Track what you eat
  • Drink more water
  • Exercise daily
  • Get more sleep
  • Make a goal and stick to it

Body Mass Index (BMI) is a measurement of a person’s weight with respect to his or her height. A BMI chart is used to categorize a person as underweight, normal, overweight, or obese.

Since BMI is an indicator of total body fat in an individual, it is considered an indicator of health risk. The higher the BMI, the greater the risk of complications associated with obesity and overweight.

A normal BMI score falls between 18.5 and 24.9. This indicates that a person is within the normal weight range for his or her height. Click here to access the Cigna BMI Calculator to calculate your body BMI.

Losing or gaining a few pounds can greatly improve your health as being overweight or obese can increase the risk of cardiovascular disease and certain cancers.

An underweight person might lack the nutrients his body needs to build healthy bones, skin, and hair, and the calories to maintain daily activities. Keeping a balanced diet and having regular exercise will help you maintain a healthy weight.


  1. Harvard T.H. Chan- Healthy Weight – Maintain, don't gain
  2. NDTV Food - Here's Why Some People Never Get Fat Even Though They Eat A Lot
  3. Live Science - Why do some people never gain weight?
  4. The Quint - Effect of Posture on Digestion: Sit Down For a Meal, Avoid Standing While Eating | Expert Advise
  5. University of Cambridge - Slim people have a genetic advantage when it comes to maintaining their weight
  6. 華人健康網 - 吃不胖真幸福?別傻了~3大健康危機埋伏中
  7. World Health Organization - Obesity
  8. Revere Health - Tips to Maintain a Healthy Weight
  9. News Medical Life Sciences - What is Body Mass Index (BMI)?

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