Leptin: Does it Make Us Fat?

Without question, among the top concerns my patients have is their inability to lose weight. And these patients are not just menopausal women & help;they are patients of all ages and both genders. Many of my patients are highly motivated; they exercise, they eat ‘healthy’, and they take their supplements and hormones as prescribed, but they still cannot drop the weight. The battle of the bulge seems to be one that most people are losing as evidenced by lucrative nature of the diet industry. Unfortunately, people are under the misconception that their body weight is controlled solely by what they eat…”Calories in = calories out”….sound familiar? Well, this is absolutely not the case. Numerous factors control body weight: Sleep patterns, food allergies, gastrointestinal health, genetic factors, stress, age, and hormonal status, just to name a few. And, by hormones, I do not just mean estrogen, progesterone, and testosterone. I am talking about the multitude of other hormones produced in your body, and in this case, your fat cells (adipocytes). Leptin is one of over thirty other hormones produced in your adipocytes. Leptin has two primary functions in our bodies: (1) when we are in energy balance and are maintaining a healthy body weight, leptin levels are an indicator of total body fat mass; and (2) in people who are actively losing or gaining weight, leptin is the hormone which signals the brain that there is an imbalance in energy flow. So, naturally during these situations, leptin levels will rise. Since leptin is responsible for telling the brain how much energy stored in adipose tissue, it plays a pivotal role in regulating body composition and metabolism. Studies have shown that women have markedly elevated leptin levels compared to men. Unlike animal studies which have shown a correlation between leptin levels and obesity, studies in humans have not reliably shown that leptin directly affects body weight. Leptin secretion does not appear to be affected by food intake and thus does not appear to control the size of a meal a person eats. Furthermore, as is true of many other hormones, leptin is secreted in a circadian pattern with levels being lowest around noon and highest during the night. This pattern seems to be maintained despite one’s dietary intake. Most evidence suggests that leptin is not directly involved in determining a person’s body weight but rather is present to insure that we maintain adequate energy stores during times that we may not have any food around. This was clearly important for our ancestors but clearly less important for us today. Most evidence suggests that patients who have elevated leptin levels may actually have developed a resistance or ‘immunity’ to their own leptin. Obesity has been shown to fuel this resistance. Given the unclear data on leptin’s role in obesity, there is no prescription or non-prescription medication shown to be of benefit. Weight loss, exercise, and consuming a low glycemic index diet are the mainstays of treatment.

 

 

Dr. Lena Edwards, MD, FAARM

 

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