The Hunger Hormone – Ghrelin

In a previous article, we discussed the key hormone leptin as it relates to hunger, weight gain and dietary adherence.

Leptin is classed as the ‘good’ hunger hormone that, when functioning normally, helps to control energy intake, hunger and overeating.  In contrast, ‘ghrelin’ is often classed as the ‘bad’ hunger hormone, linked with increased hunger and poor dietary adherence.

Ghrelin is produced in the stomach and the levels produced are dependent on many factors including fed state (e.g. when you ate your last meal), other hormones such as leptin and growth hormone, and then things such as age, gender, fasting blood sugar and insulin levels.

Ghrelin’s daily mechanisms can be broken down into 2 simple stages

1. We eat food, ghrelin decreases, this lowers hunger and our desire to eat.

2. Around 3 hours after eating, ghrelin levels start heading back to a baseline level, meaning hunger increases.

While the daily functions of ghrelin are normal and remind you to eat, the issue occurs when ghrelin levels change or become elevated, which means your perceived hunger increases.  This often causes poor dietary adherence (think how many people quit diets or binge because they are excessively hungry), poor food choices, overeating, and rapid weight gain.

Understanding this hormone is therefore crucial for any physique competitor, bodybuilder, athlete, fitness enthusiast or coach.  By keeping this hormone under control, dietary adherence and weight management will become much easier.  These populations often engage in repeated dieting in an attempt to optimize their physique or performance, but research has shown that when you diet, ghrelin rapidly increases, which means hunger rapidly increases with it.

If you have dieted in the past, you will know firsthand how hunger constantly increases.  The changes in ghrelin help explain this. measured ghrelin levels following a 6 month weight loss intervention program and found a 24% increase in ghrelin levels.  In addition, when investigated a male bodybuilder during a 6 month prep phase and witnessed around a 40% increase in ghrelin levels after 6 months of dieting.

The post-diet or post-contest weight rebound is well known, along with the psychological eating ‘issues’ many competitors face.  This is likely caused by rapid elevations in ghrelin during the prep period, especially if these diets happen multiple times per year.  It’s not unlikely in these cases that that ghrelin skyrockets on occasion, so don’t be surprised if you suddenly find yourself bingeing on 8000 calories in the buffet at some point!

Therefore, to make dieting easier, long-term weight management more successful, and people’s psychological relationship with food more healthy, one should aim to manage ghrelin and keep it within a normal range.

Here are some high-level actionable dieting tips to help limit ghrelin and hunger adaptions caused by dieting

  1. Supplement with around 20g oligofructose (Inulin) per day.  One study provided participants with 21g oligofructose per day for 12 weeks and found a decrease in ghrelin levels, energy intake, blood glucose and insulin levels (Parnell 2009).
  1. Eat high protein meals!  Along with all the other benefits protein provides, it is renowned for increasing satiety through several separate mechanisms, one of which is the reduction of ghrelin, compared to isocaloric (matched calories) carbohydrate meals.
  1. A low carb diet, in general, may help with satiety when dieting as it helps to maintain low ghrelin levels.  One study found that when participants went back to their typical Western diets following a ketogenic diet, ghrelin was significantly elevated (Sumithran 2013).
  1. Cycle your calories.  Shorter duration diets may be a novel strategy to help control some of the metabolic adaptions to weight loss.  For example, prolonged dieting reduces Leptin, slows your metabolism, and increases ghrelin.  Therefore, by doing shorter blocks of dieting, interspersed with higher calorie blocks, it may be possible to offset some of these adaptations.

Two example strategies for a fat loss calorie cycle may be

  • Diet for 11 days, followed by a 3 day re-feed to get back up to baseline.
  • Diet for 3-4 weeks followed by around 1 week to bring calories back up to baseline.

In Summary

It’s important to consider the integrative role that leptin and ghrelin play.  One strategy used to counteract this is tracking calories / setting a daily food intake.  Although this helps combat some of the free-eating issues, constant hunger and lack of satiety will likely make the weight-loss journey hard, possibly even unsuccessful in the long-term.

The issues apparent with leptin and ghrelin when dieting highlight the importance of a conservative growth phase, or “lean bulk”.  A large amount of added fat mass may increase leptin resistance, and, furthermore, mean a longer time spent dieting to get rid of it, which will negatively impact ghrelin levels. 

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