Are your hormones making you fat?

Is there some more going on, beyond calories in, calories out, when it comes to weight loss?  Is there more to losing fat than just eating less and exercising more?  There can be……… read on.

Unless we are regularly eating far more calories than we need, weight tends to stay within a narrow range referred to as our ‘set weight’. Despite daily fluctuations in energy intakes and activity level the body maintains weight close to this point, as this is where it is ‘happy’.

When we change dietary habits and increase physical activity in an effort to lose weight and move away from this point, the body tries to get it back again. This is why sometimes with weight loss strategies, people see results initially and then they plateau off and nothing else happens despite weight loss efforts being maintained. The body has several ways of doing this.  Firstly, it lowers your basal metabolic rate, which is the energy expended to maintain vital functions. This means you are burning less energy.

Secondly, various hormones can come into play.

Ghrelin – is a hormone secreted by the stomach in the absence of food. It travels to the brain and activates centres that tell you you’re hungry, thus increasing appetite. Ghrelin levels are high in fasting conditions and calorie restriction.  I don’t know about you but being hungry is one of my least favourite feelings. Unfortunately, Ghrelin’s actions means that feelings of hunger often increase when weight is lost, triggering an increase in food uptake, and all too often bringing us back to square one.

Leptin – is an important hormone affecting our satiety (fullness). It is released by our fat cells in proportion to how much fat we have, and it informs the brain of the status of our energy stores (fat!), which in turn affects our appetite. When we lose weight, fat stores are lower so Leptin levels drop, and satiety decreases, prompting us to eat more. It also has roles in energy expenditure and can reduce this in response to a drop in fat stores. Both of these actions promote the regaining of fat.

Another hormone that affect food intake is Cholecystokinin (let’s just call it CCK). This is released by the small intestine in response to protein and fat and helps us to feel full. This means that fat and protein are more satiating than carbohydrates. Protein in particular can be helpful for weight loss as it has a lot less calories per gram than fat does.

Additionally, Insulin and Glucagon are antagonistic (opposing) hormones which play a role in fat loss and fat gain. Insulin is released in response to carbohydrate (glucose) intake in the diet.

Glucagon is released when blood glucose drops and promotes the breakdown of glucose to provide energy.   Glucagon's main job is to keep blood glucose from dipping too low.  In general, insulin is the bad guy and glucagon is the good guy when it comes to fat loss.

The role of insulin:

  • lowers high blood sugar.
  • puts the metabolism in storage mode.
  • converts protein and blood sugar to fat.
  • causes fat in the diet to be stored in fat cells.
  • increases the production of cholesterol by the body.
  • causes the kidneys to retain water in the body.
  • stimulates the growth of artery wall cells.
  • stimulates the use of blood sugar for energy.

Glucagon works in opposition to insulin and has the opposite effects:

  • raises low blood sugar.
  • puts the metabolism in burning mode.
  • converts protein and fat to glucose.
  • causes dietary fat to be used for energy.
  • releases fat from fat cells to be used for energy.
  • reduces cholesterol production.
  • causes the kidneys to release water from the body.
  • causes artery wall cells to return to normal.
  • stimulates the use of fat for energy.

Pretty obviously we want to keep these hormones in the right balance if our goal is fat loss and good health.  What we eat will have the biggest influence on this.  Getting your protein and carbohydrate intake correct will influence the levels of these two hormones.

You’ve probably heard the term ‘glycaemic index’ mentioned in regards to nutrition. This is an important concept for weight loss and health in general. The glycaemic index (GI) of a food is the rate at which carbohydrate (broken down into glucose) is released into the blood stream. High GI foods such as white bread, Jasmine rice, etc, give a rapid rise in blood glucose. This means that there is also a rapid rise in insulin. Your body will use the amount of glucose it needs for energy and store any excess as fat. With low GI foods such as wholegrains, the blood glucose rise is slower and more sustained, and therefore less insulin is released at once. With high GI foods, there is a greater likelihood of more glucose being released at one time than our body needs for energy increasing chances of fat storage compared with the slow release low GI foods. In addition to this high insulin levels can lead to our tissues becoming insulin resistant meaning the cells no longer respond to insulin so glucose remains in the blood. Insulin resistance is a major risk factor in the development of Type II diabetes.  Type 2 Diabetes is a huge issue in New Zealand and it is estimated that by 2021 nearly half a million New Zealanders will have type 2 diabetes.

The take home message is that elevated insulin levels are detrimental to fat loss and good health.

Coming back to the ‘weight set point’ the good news is if you persevere with the changed dietary habits and exercise, your body can reset the ‘set weight’ to a lower level. It just takes time and consistency. If you give up and go back to old habits you will find yourself back where you started, or worse. So be aware that there is likely to be a ‘slump’ in weight loss where nothing seems to be happening. This is due to normal physiological processes in our bodies attempt to maintain its ‘set weight’. If you can push past this point you should start to see results again and you’ll be on your way to resetting that ‘set weight’ at a happier and healthier level. The key is long term lifestyle change in the form of healthy dietary habits and physical activity – short term diets will only result in a weight rebound once they are neglected!


As you can see, yes, hormones can play a part of slowing down of fat loss, but before you blame your hormones, check out these important issues.

  • Is the composition of your diet correct?  (i.e. the optimal amount of carbohydrates, protein and fat for your body)
  • Are you choosing low GI carbohydrates?
  • Are you measuring your portions?  Portion distortion is alive and well in most homes!
  • Are you aware of what is going in your mouth, or are there ‘bits and pieces’ creeping in during the day which you aren’t taking into account.
  • Do you realise that fruit juices, fizzy drinks, energy drinks, café coffees and alcohol are liquid food? Don’t forget to take them into account.
  • Are you exercising and then thinking “well I’ve exercised so it won’t matter if I have………”!

For most people, weight loss is absolutely achievable with the right advice, the right attitude and stickability.

Posted on August 21, 2014 .