Here's the list:
Each of these hormones plays a distinct role in weight gain and loss. When and how they play their role is still a matter of some debate, but we know that we can control them to some extent.
So when somebody, or for that matter anybody, tells everybody exactly why they get fat, consider it rubbish. As a doctor that treats obesity and related weight problems, I can tell you honestly that it's a different reason in every case. Many claim the reason is the conventional wisdom that it's simply "calorie in, calorie out," but they would be wrong because not all calories are created equally. For example, recently it was discovered that the fat in nuts are not as well absorbed as previously thought due to the fat's attachment to the fiber which prevents full absorption, and therefore it turns out that nuts produce less calories than previously believed. However, the biggest problem with "calories in and out" is the simple saying doesn't explain why you may have a problem controlling your calorie intake.
Most people gain weight because of a combination of five main reasons, but in each case each reason contributes a different percentage and that's why each person is different. The reasons include an underlying medical condition, a sedentary lifestyle, a poor diet, insufficient sleep, and undue stress. Diet is a usual suspect. Yet for example, undiagnosed thyroid disease can be a major culprit in weight gain, but it can only be diagnosed definitively with a medical assessment including blood test. For sleep related problems, it's well known that insufficient sleep affects the hormones ghrelin and growth hormone, releasing them in greater amounts. Both these hormones cause increased appetite, which leads to added weight. Don't even get me started about stress and sitting around all day.
So when evaluating someone with a weight problem, the only reasonable and meaningful approach is to systematically identify his or her own root causes and then develop a plan to address the guilty parties. My practice does this with a combination of factors including:
1. For medical: evaluation by a MD
2. For stress, emotional and psychological support: counseling by a Clinical Psychologist (PhD) who also leads a weekly mindfulness meditation class; massage therapy and acupuncture to help people relax
3. For nutrition and diet: nutritional counseling, meal planning, and food shopping by a registered dietitian/nutritionist who also leads healthy cooking classes
4. For exercise: support through cardio and yoga classes
5. For sleep: sleep hygiene counseling and referral to a sleep study as needed
By tackling each of these areas individually and collectively, we help people get healthier, feel better, and -- lose weight.
So when someone tells you off the cuff, or you read in a magazine or a book, why you gained your weight, just ignore them. Until they know you, they really don't know why you gained weight. There are healthy and unhealthy ways to lose weight, and which way you choose can have a profound impact on your long-term health.