A balanced guide to hormones and how they regulate your weight
Hormones are chemicals that the body creates to send messages around the body. They are capable of switching things on and off or speeding up and slowing down bodily functions. Adrenaline, for example, will speed up heart rate and breathing rate among other things when you need to run away from something. Glands are the things in the body, often organs, which produce hormones. Why do we have them? Your body works best when it is in homeostasis, or normal, balanced functioning. There are times though when it needs to work faster and others when it needs to slow down. Hormones are triggers that switch things on or off, speed up or slow down things like heart rate, and increase or decrease levels of things like blood sugar, dependent on what the body needs. Ideally the body will work in a balanced way, so it will be down as much as it is up and off as much as it is on. The right balance of hormones helps this to happen. How do they affect weight loss and weight gain? Hormones have many roles in the body and a number are involved in the production and storage of energy, the regulation of appetite and in helping the body release energy when needed to for movement and exercise. These all have a bearing on how much fat a person stores at any one time and how much weight they lose or gain. The main hormones you should be aware of are identified below. Insulin and glucagon These two hormones, insulin in particular, play a major part in the storage of fat within the body. They are effectively complete opposites and should work together to regulate blood sugars up and down when required to keep your body functioning normally. Glucagon is released when blood sugars drop. This may occur if someone has not eaten for a while or has exercised and their blood sugar levels have decreased as a result. Glucagon is released by the pancreas and through a chain of events causes the liver to release the body’s store of glucose (known as glycogen) into the bloodstream. This elevates blood sugar levels and enables the person to function properly. In evolutionary terms, glucagon was a very useful hormone as it was needed in times of ‘fight or flight’ to elevate blood sugar levels. It also came into play if a person went a while without food. The brain needs a steady supply of energy, so if it couldn’t be supplied by food the body was able to dip into its back-up stores to increase blood sugars and give the brain the fuel it required. We have maintained all of these evolutionary functions and they are still useful in today’s world, although in Western society it is very rare for people to go any length of time without access to any food at all. It has not been shown that any discrepancies in glucagon levels bring about obesity, but it does appear that in overweight individuals, glucagon may not be as effective at raising energy usage as in normal weight people (Starke et al, 1984). Insulin is one of the most important hormones when it comes to weight gain and associated medical conditions, especially diabetes. It has a number of jobs but its major role is to decrease blood sugars if they get too high. These days this can happen a lot with our highly processed and refined, high sugar diets. Each time a person consumes a chocolate bar, some white bread or a can of fizzy drink, insulin is called into action as the level of glucose in the blood soars above what is required. The body responds by pulling this glucose out of the bloodstream and into storage just in case it needs it later. If stores of sugars are full then instead of wasting it, the body converts it to, and stores it as fat. If this happens regularly over time, the body becomes less sensitive to the insulin and blood sugars will stay high. In response to this the body releases more insulin to get the desired response. This keeps happening until the body becomes extremely insensitive to insulin and blood sugars remain high most of the time. This is diabetes type 2. It can get even worse; if the poor lifestyle persists the pancreas gets exhausted from having to produce so much insulin and effectively gives in. These later-stage diabetics aren’t just insensitive to insulin, they often don’t produce any and rely on injections to get what they need and help their body regulate its blood sugar levels. Coupled with this the high levels of glucose can cause damage throughout the body and weight control becomes extremely challenging. It has been argued by some that the insulin response and the body’s subsequent insensitivity are the major factors in the obesity epidemic (Taubes, 2013). This argument is commonly used in many of the high fat, high protein, low-carb diets that have been popular over the last 20 years that are reviewed in more detail in the nutrition chapter. There is a growing support for higher fat diets in science, especially for those people with diabetes where low-carb diets may improve insulin sensitivity and reduce the subsequent risks. Guldbrand et al (2012) showed that over two years a low-carbohydrate diet containing 50 per cent fat and 20 per cent carbohydrate led to a significant drop in blood sugars in diabetic patients, allowing them to reduce their insulin medication. This was not seen in a group consuming 60 per cent carbohydrates and 30 per cent fat as per current government recommendations. Marshall and Bessesen (2002) however argue the opposite, noting that many studies suggest that high fat diets are shown to impair insulin function – and so the debate rages on. Leptin and ghrelin Along with insulin, another hormone that has received huge attention in recent years in relation to fat storage is leptin. It is produced mostly by the
