What Causes Weight Gain?
Weight gain happens when calorie intake consistently exceeds calorie expenditure, but factors such as hormonal imbalances, insulin resistance, poor sleep, chronic stress, certain medications, genetics, and highly processed foods can also contribute.
Key Takeaways
- Weight gain depends on biological, behavioral and environmental factors.
- Leptin and insulin are hormones that influence the regulation of appetite.
- Weight gain can be caused by sleep disturbance, stress, medication or lack of exercise.
- Meal planning and selecting nutritious foods can aid in healthy weight management.
- If weight gain is ongoing or unexplained, it’s important to consult with a health care professional.
There are many things that hurt my heart when I meet someone who has been trying, and failing, to lose their excess weight for a long time. But the number one is seeing a beautiful, accomplished person who has developed self-loathing, simply because their weight-gain has made them think they are weak-willed and incapable.
What they don’t know is that, in today’s world, the problem starts in parts of the brain we have little control over. As a brain and cognitive scientist, and Professor of the Psychology of Eating, I want people to understand how the brain makes us gain weight and keep it on. There are specific reasons for weight gain and you need to be aware of them, as well as of weight gain foods.
First, we must understand the new hunger. Real hunger is your body’s natural response to needing fuel. But now we also have an insatiable hunger, the kind that cues you to eat two or three helpings of dinner, then move to the couch with a bag of potato chips, followed by a carton of ice cream, and still sends you to bed feeling unsatisfied. Stuffed and vaguely sick, but unsatisfied.
After years of research, scientists have finally figured out what is causing insatiable hunger: it’s the brain’s inability to recognize the hormone leptin. Leptin is what cues the brain to tell us we’re full and ready to move. Without it, we behave just like the mice born without it, who literally ate themselves to death. However, overweight humans aren’t leptin-deficient. They actually have larger amounts of leptin in the bloodstreams than thinner people. Their brains are just incapable of seeing it.
So what’s blocking the modern brain from seeing leptin? Insulin. The current global diet is so much higher in sugar than it was thirty years ago causing people insulin levels to be higher. Elevated insulin is not only giving 1.4 million new people in the U.S. Type 2 Diabetes every year, but it is also making them relentlessly, exhaustingly, hungry.

Food Cravings Concept
Second, we live in a culture that has normed cravings. People assume that cravings are cues from our brains that we need a hit of some vitamin or mineral our bodies are running low on. Like sailors getting scurvy must have craved citrus. Pregnant women, growing an entire skeleton, must crave dairy. But no one has stopped to think that it makes no sense, ever, for us to be “meant” to crave a venti mochaccino or a hot fudge brownie sundae. It’s not a biofeedback mechanism; it’s an addiction.
When the center of pleasure, reward, and motivation in the brain, known as the nucleus accumbens, is repeatedly hit with any sort of excessive stimulation, the nucleus accumbens down-regulates in order to protect itself. To do this, this area of the brain turns off some of the pleasure receptors to avoid being bombarded with the same intensity in the future. It does this in response to porn, drugs, alcohol, and sugar. That’s why when you place an order for the bear claw again next time, you will not experience the same degree of satisfaction you enjoyed the time before. You will still introduce the same amount of sugar to your body and brain, however. So the brain will respond once again by switching off even more receptors.
Eating heavily processed foods with sugar, fat and salt frequently has been found to affect the brain’s reward mechanisms. Several studies have revealed parallels between the neural mechanisms involved in overfeeding and those found in substance abuse disorders. But obesity is a multifaceted condition that is shaped by biology, psychology, environment and lifestyle, and the link between food reward and addictive-like eating continues to be an area of research.
When I first learned about this, it completely resonated. I thought back to being obese myself, eating marshmallow after marshmallow out of my coat pocket in the middle of the U.C. Berkeley campus, getting no pleasure from it, feeling totally sick, but compelled to do it over and over again anyway.
When I tried to diet, I threw myself in with my whole heart, harnessing the same determination that had gotten me sober from drugs and alcohol, which had taken me from high-school dropout to student speaker at Berkeley’s graduation. But when it came to food I couldn’t do it. I couldn’t seem to summon the willpower.
Thank God I eventually found out that willpower is perhaps the greatest culprit of them all. Because we completely misunderstand it. We think it’s a dimension of character and we well-meaningly tell people they just need “more” of it. We credit slender people as just having a lot of it, and malign overweight people by thinking they have none. When, in reality, they have exactly the same amount.
Willpower is the cognitive function that governs all types of self-regulation, and our brains get about fifteen minutes of it to draw down from at a time. Our brain uses it so we can keep our patience, stay off Instagram at work, and stick with tasks we’d rather put down. Once the glucose in that part of the brain is used up, it becomes almost impossible to continue to self-regulate. If you are then making a food choice at that moment, you’re a sitting duck. You are going to give in to your insatiable hunger or overpowering craving, instead of sticking with your plan for losing weight.
For a diet to work long-term it must anticipate that you will run out of willpower multiple times every day and still work anyway. In my experience and my research, the key is never making food decisions on the fly. We cannot trust our brains to act in our best interests when the brain stem has blocked leptin, the nucleus accumbens is telling us we’ll die without a donut, and our willpower has run out of glucose.
In my program, Bright Line Eating, which is rooted in all of this science, we plan out our meals the night before. Then all we have to do from sunup to sundown is follow what the well-rested, well-fed, best-intentioned parts of our brain wanted for us all along. This takes the burden off willpower and, by making good food choices consistently, allows the brain to heal. The pleasure receptors come back. The brains starts recognizing its leptin, and you start feeling full and energetic.
How do you gain weight healthy?
If you want to gain weight in a healthy manner, the first thing you have to do is pay attention to the food you are eating. Choose only fresh produce, rich in vitamins, minerals and other beneficial nutrients. Eat lean meat, from quality sources and plenty of nuts, seeds, as these provide you with an increased intake of healthy fats. Do not forget about fatty fish, as this is rich in omega-3 fatty acids. And work out, as this will help you build muscle tissue.
How can I put on weight without eating sugar?

How to gain weight without sugar
As it was already mentioned above, you have to seek out proteins and healthy fats from top quality sources. Sugar is highly addictive, so you need to eliminate it completely from your diet. You should also consider engaging in physical exercise, as this can be beneficial in developing muscles.
What should I eat to gain weight in a week?
If you want to gain weight in a week, the first thing to do is set a specific goal to reach. Then, you should arrange a meal schedule, making sure that your meals are rich in proteins and healthy fats. You can also eat complex carbs, as these are released on a gradual basis and they do not have a negative impact on your blood sugar. So, you should eat fresh fruits and vegetables, lean meat, fatty fish, nuts and seeds, whole grains etc.
Do dietitians help you gain weight?
If desired, yes, dietitians can help you gain weight. They can make a preliminary examination and determine your actual weight gain needs. Based on this initial assessment, they will help you set a weight gain goal and suggest types of foods you can include in your daily meals. You might even receive recommendations for meal planning. The big advantage is that you will only receive advice about healthy foods.
How can women gain weight?
Women can gain weight by following a diet as suggested above, as well as by including physical exercise in their daily schedules. It is important to note that women are more susceptible to accumulating fatty tissue, as it is for the best to consume more proteins than fats.
It’s simple, but powerful. Until we understand and accept that weight gain starts in the brain, we won’t be looking to the right place to reverse it. Acknowledge the real reasons for weight gain and you would have already taken the first big step. And, remember, there are weight gain foods you should avoid at all times.
Conclusion
The process of gaining weight is complex and involves numerous biological, hormonal, behavioral, and environmental factors. While many of the factors that regulate hunger, choices of food, and how the brain talks to the body about those choices may be involved; it is primarily dependant upon our stereotypical habits (e.g. food choices; sleeping habits; how we physically relieve stress; and the amount of exercise we perform) that will have the biggest impact in this situation. Understanding the underlying reasons will help you achieve your goal of maintaining a healthy weight and a healthy body through proper decision-making and finding sustainable ways to maintain the results.
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2 Sources
We review published medical research in respected scientific journals to arrive at our conclusions about a product or health topic. This ensures the highest standard of scientific accuracy.
[2] Physiology, Obesity Neurohormonal Appetite And Satiety Control : https://www.ncbi.nlm.nih.gov/books/NBK555906/

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