The Link Between Carbs and Weight Gain

Aditi Shenai

June 1, 2022

Carbohydrates form an essential part of your diet. They provide you with energy, similar to how gasoline gives fuel to a car. Carbohydrates also aid digestion and triglyceride metabolism and keep blood cholesterol levels in check. Despite their essential role in your body, carbohydrates have a bad reputation. The misconception that carbohydrates are fattening prevents people from consuming a properly balanced diet. As a result, most of us believe carbs are an enemy in our weight loss journeys and try to avoid them altogether. However, cutting off carbs is far from ideal and is not sustainable. To make healthy choices, you need to know the difference between good and bad carbs, mainly how they affect your weight.

Carbohydrates: An Introduction

Carbohydrates are among the three macronutrients required in your diet, including protein and fats. They contain carbon, hydrogen and oxygen atoms, which act as a significant energy source and help control blood glucose levels. Carbs also participate in cholesterol and triglyceride metabolism. Carbohydrates are present in many foods like sugar, fruits, vegetables, and legumes. While there are numerous varieties and divisions of carbohydrates, only a specific subset is considered healthy.

Types of Carbohydrates

Based on Structure

Based on the structure, carbohydrates classify into monosaccharides and polysaccharides. Therefore, the structural complexity increases from monosaccharides to polysaccharides. 


They form the most basic structure of carbohydrates and are simple sugars. Therefore, monosaccharides do not require a further breakdown by the body. Some monosaccharides are glucose, fructose, and galactose.


They are sugars that contain two molecules of monosaccharides. One of the primary examples of a disaccharide is lactose. Your body breaks down lactose with the help of the enzyme lactase. Another example is sucrose. It is the most common disaccharide in sugar, cane sugar, beets, honey and maple syrups. Sucrose is also present in white, brown or powdered sugars. It is something you should consume in moderation while watching your weight. A study shows that high sucrose intake was associated with long-term weight gain.  


These are long chains of monosaccharides that are difficult to digest by the body. They are complex and require a long time for a breakdown. An example of this sugar is amylase and cellulose. Polysaccharides do not negatively impact your weight. 

Carbs Based on Metabolic Effect

Based on the effect of carbohydrates on blood sugar levels and their impact on insulin, there are simple carbohydrates, complex carbohydrates and fibre.

Simple Carbohydrates 

As the name suggests, simple carbohydrates are simple sugars, monosaccharides or disaccharides like glucose, galactose, lactose, sucrose and maltose. Our bodies efficiently utilise them and cause an immediate surge in blood glucose and insulin levels. It is the type of carbs that cause weight gain. 

Complex carbohydrates

Complex carbohydrates are complex polysaccharides like amylose, cellulose, dextrin and rutinulose. These take longer to digest and raise blood glucose levels slowly instead of the rapid surge. Complex carbohydrates also include a subgroup known as starches, primarily produced by plants. Complex carbs are good carbs for losing weight. 


Fibres are complex carbohydrates that encourage healthy bacterial growth in the colon. They also act as a bulking agent; they increase the bulk and soften stool, thereby easing defecation. Bulking action of fibre increases the regularity of bowel movements. They are also known to reduce blood cholesterol levels and lower post-meal blood glucose levels. The main components of fibre are cellulose, hemicellulose and pectin.

How Do Simple Carbohydrates Cause Weight Gain?

The glycemic index (GI) measures how much a specific food can increase your blood sugar levels. Simple carbs have a high glycemic index, inducing blood sugar spikes. A study indicates that weight gain from simple carbs is due to a sudden increase in blood sugar levels. The rapid rise in blood glucose levels triggers a strong insulin response which inhibits nutrient mobilisation. It equates to increased glucose uptake and glycogen storage. Unfortunately, the excess glycogen is also converted into fat, leading to weight gain.

Satiety also appears to be a potential mechanism related to high glycemic index and weight gain. Low glycemic index carbohydrates delay hunger and decrease the subsequent intake of food. On the contrary, simple carbs with a high glycemic index undergo fast digestion. Therefore, it does not keep you satiated and triggers hunger. These untimely cravings lead to overeating and frequent snacking, resulting in weight gain.

Complex Carbohydrates and Their Impact on Weight

Complex carbohydrates are known to aid in your weight loss journey. A research review indicates that the healthiest sources of carbohydrates are complex carbohydrates as they have beneficial effects on blood glucose. They are also slowly digested, which gives a feeling of fullness. It prevents excess calorie consumption and aids in weight loss. Some options include unprocessed whole grains, vegetables, fruits and legumes. Various phytochemicals in these foods break down the fatty deposits, which helps in weight loss.

Here are some of the various complex carbohydrate options to add to your diet.


Grains, the seeds of cereal grasses and similar plant families are significant sources of dietary carbohydrates worldwide. Whole unprocessed or minimally processed grains are complex carbohydrates, while processed carbohydrates are simple carbs. Studies have indicated that whole grains are not associated with weight gain and instead make a part of a nutritious diet. The results also suggest that whole grains reduce low-density lipoprotein (LDL) cholesterol, total cholesterol, and body fat percentage. In addition, these complex carbs help maintain weight by improving postprandial glucose levels and glucose homeostasis. 

Prospective studies have also shown associations between whole-grain intake and reduced incidence of type 2 diabetes, coronary heart disease, ischaemic stroke, and cancer. Whole grains also have phytochemicals with potential anti-inflammatory and antioxidant properties. These phytochemicals also aid in your weight loss journey. 

Some healthy whole grain options are:

  • Brown rice
  • Quinoa
  • Oats
  • Millets
  • Barley


Legumes such as beans, peas, and lentils improve nutritional quality when included in the daily diet. It contain complex carbohydrates and relatively high amounts of protein, fibre, and other nutrients. They are known to be filling and reduce unwanted cravings. It helps in controlling the calories consumed and helps in weight loss. 

Black bean is a dark legume with the highest antioxidants, forming a solid defence against heart disease. But, of course, other beans such as lima, navy, pinto, fava or kidney are still packed with fibre and protein. Most weight-loss diets contain beans and lentils. The latter is also a complex carb source rich in fibre, protein, and nutrients such as folate, manganese, and iron. They help reduce weight and decrease body fat percentage. So if you’re looking for a low glycemic index complex carbs, choose green lentils and beans. 


Whole fruits are high in complex carbs, fibre, vitamins, minerals, and phytochemicals. These phytochemicals aid in weight loss, according to research. In addition, fruits with high water content provide satiety and decrease the number of calories consumed. Whole fruits typically have moderate to low Glycemic index and can be consumed by people with diabetes. However, you need to monitor the portion sizes. Stick to fresh fruits since bottled fruit juices have simple carbs, less fibre, fewer micronutrients, and a higher glycemic index. And for these reasons, it is recommended to consume whole fruits.

Do We Need to Avoid Carbs for Weight Loss? 

On average, healthy adult diets should include 45%-65% carbohydrates as a part of daily intake. However, the thinking that carbs cause weight gain comes from the Atkins diet and other popular low-carb diets and meal plans. However, nothing justifies cutting carbohydrates entirely from your diet. 

Eating carbs in limited amounts can lead to weight loss, but it doesn’t mean that the simple act of eating carbs causes weight gain in the first place. Of course, added sugars and refined carbs lead to an increased chance of developing obesity. The same is not valid for fibre-rich, whole-food sources of carbohydrates. Humans have been eating carbs for thousands of years, in some form or another. Yet the rate of developing obesity started growing around the mid-20th century. Therefore, it indicates that our lifestyle plays a vital role in deciding the weight range. 

It’s also worth noting that some populations have remained in excellent health while eating a moderate carb diet. For example, the Okinawan people and Mediterranean people, who consume a significant portion of their daily calorie intake from carbohydrates, have some of the most extended lifespans. What they have in common is they eat natural, unprocessed foods. However, studies show that populations that consume excess refined carbohydrates and processed foods tend to have a higher chance of developing harmful health outcomes. 

The bottom line is to focus on a sustainable weight loss journey. Of course, it all depends on what else you’re eating every day and what makes up your calorie deficit. First, however, it’s essential to be mindful of the carbs you choose to consume. Remember, balance is crucial, consuming carbs is normal, and you don’t need to eliminate them.

Tips for Eating Carbs 

  • Choose whole grains and not refined grains.
  • Try to avoid foods with added sugar. These foods can have empty calories and simple carbs but not much nutrition. Plus, empty calories contribute to weight gain.
  • Watch your portion size. It is essential to understand that increasing the number of calories contributes to weight gain. 
  • Find a healthy balance between carbohydrates and other nutrients. Strictly low carbohydrate diets are unsustainable in the long run.
  • Drink green tea 15-30 minutes before or after a high-carb meal. It is a good diet strategy because the antioxidants in green tea combined with carbohydrates can help regulate hunger hormones and boost healthy metabolism.
  • Instead of slashing carbohydrates from your diet, remove liquid carbs because liquid carbohydrates are 17% less filling than solid carbohydrates. So, as a general rule: eat, don’t drink, your carbs.


The truth behind carbs is that you can include them in your diet as long as you choose the right ones. Simple or refined carbohydrates cause a rapid increase in your sugar levels and are generally converted into fats and cause weight gain. These simple carbs are why carbohydrates have gotten such a bad image. However, it is not valid with complex carbs, which take much longer to digest and cause a slow rise in sugar levels. In addition, many don’t understand that liquid carbs in bottled fruit juices, sports drinks, soda, and alcohol are even worse than solid, simple carbs. So, before jumping into a restrictive carbohydrate diet, it is essential to understand the type of carbs and their various adverse effects on your weight.

Frequently Asked Questions (FAQs)

Q. Which carbs make you gain weight?

A. Refined carbohydrates, also known as simple carbohydrates, make you gain weight. These are present in processed white flour, white bread, white rice, pastries, sodas, pasta, sweets, and breakfast cereals. They are digested rapidly and stimulate cravings, leading to overeating and weight gain.

Q. Are carbs good for gaining weight?

A.Refined carbs are responsible for gaining weight. However, this method is usually not recommended as carbs are responsible for adverse health conditions like cardiovascular disease and type 2 diabetes mellitus. Instead, protein-rich diets can promote healthy weight gain. Carbs don’t cause weight gain unless they contribute to excessive calorie intake.

Q. What makes you gain weight fast?

A. Calorie surplus diet helps you gain weight fast. You can achieve it by consuming more calories than those burnt. Protein-rich diets and muscle building exercises are your obvious choice to gain weight healthily.

Q. What food makes you gain weight the fastest?

A. Having simple carbohydrates or refined carbohydrates consistently of high quality can help you gain weight fast as you will be in a calorie surplus. However, it is highly unhealthy. Weight gain must be a gradual process and not some quick fix. 

Q. How can a skinny person gain weight?

A. If you are skinny, you can gain weight by building muscle. It is, however, not a very easy process. First, you need to consume protein-rich foods and should be in a calorie surplus. It is also essential to exercise and train your muscles. 

Q. Do carbs make you gain muscle?

A.Carbs alone cannot help you gain muscle. A protein-rich diet accompanied by complex carbs can help you achieve your goal. Carbohydrates will help you give the energy to work out while protein-rich foods build the muscle.

Q. What food makes you thick?

A. Milk, rice, protein smoothies, starchy foods like potatoes, salmon, dried fruits, whole-grain foods, avocados, and cereal bars can help you gain weight. However, it would help if you were in a calorie surplus and exercised regularly. Staying physically active is essential to prevent any diseases related to consuming these rich foods.

Q. What are the three foods that make you fat?

A. Frozen pizza, processed meats, and sugary drinks top fattening foods and beverages. They are simple carbs or refined carbs which make you fat and unhealthy. In addition, ultra-processed foods, deli meat, desserts, and fast food makes you fat.  

Q. What foods have a lot of calories to gain weight?

A. Foods high in calories are called calorie-dense foods. For example, breakfast cereals, fries, avocado, butter, nuts, fatty cuts of meat, pastries, chips, candy and sugary drinks contain high calories. 

Q. What protein shakes help you gain weight?

A. Drinking homemade protein smoothies can be a highly nutritious and quick way to gain weight. Whey protein, casein protein, soy protein, hemp protein, rice protein and pea protein are popular protein powders that can also be had to help gain weight. 

About the Author

M.Sc in: Dietetics and Applied Nutrition from Manipal University. Worked: All over India and have been involved in helping set up nutrition departments in start ups. Interested in lifestyle based nutrition. Mantra: A healthy lifestyle isn't a choice to be made or discarded, it's a way of life!

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