You don’t want it bad enough. Or do you?

Self-control is the cornerstone of New Year, New Me diets. It is the cause and solution to your body image woes. You could have your dream body, but you don’t want it bad enough.

You can’t control yourself around food. You can’t say no. If only you could stick to the kale and human tear diet. All of your problems would disappear, right?

Self-control has long been purported as a finite resource. And as anyone who has ever embarked on a really restrictive diet can attest to, it runs out pretty quickly the more you test it.

However, restrictive diets are still commonly recommended and followed by millions of people. Especially around the time of #NewYearNewYou, when your blood type is 50% Bailey’s and 50% Christmas ham. However, are you setting yourself up to fail by embarking on a detox/juice cleanse/hypocaloric diet?

Let’s see what our good friend science has to say about self-control, willpower and behaviour change.

Self-Control as a Finite Resource

We use self-control every day, to varying degrees. When you decide to get up and not sleep in, not to quit your job when it gets busy, or go to the gym instead of going home to Netflix, you use self-control. It is obviously beneficial for us to use self-control to achieve our goals and function well as a society. A society driven by impulse and hedonism would be a shitshow.

Baumeister[1] has long suggested that our self-control is limited, and that when we use self-control in situations, we experience what’s called ego depletion. Ego depletion draws on our “willpower” and “motivation” to get the job done. The more we use our self-control, the more exhausted we become[2]. This is well-demonstrated in literature. Participants in a study requiring self-control to carry out two consecutive tasks repeatedly performed worse in the second task[3]. This may be because we have “exhausted” our supply of self-control in the first task, leaving us with little to none for the second task.

Baumeister[1] has likened our self-control to a muscleit gets stronger the more you use it. It replenishes with rest and recovery. We can also overload it, and burn out if we try and do too much too quickly.

What does this mean for dieting?

To me, it explains why these hyperrestrictive diets don’t work. They require too much of your self-control too quickly. You focus a lot of your energy on “resisting” your old ways, foods you love and your own hunger signals. You haven’t given yourself a chance to adapt and change. Is it any wonder they rarely succeed long-term?

It is also a positive for the slow and steady habit-based diet and lifestyle change. Gradual changes are sustainable and can strengthen your self-control!

The Theory of Planned Behaviour

According to the Theory of Reasoned Action, our behaviour is determined by our intentions. Our intention is guided by societal norms and our attitude[4]. If we think a behaviour will grant us approval and status, we are more likely to do it. The Theory of Planned Behaviour (TRB) is an extension of this. TPB links our intentions with our behaviour[5]. It places a huge emphasis on our attitude. Our attitude consists of our beliefs, knowledge, values and perception of a behaviour as “good/bad”. Using TPB to alter dietary behaviour has been highly effective in adolescents[5]. However, we must remember how easily influenced teenagers are (see my horrendous panda eyes and skinny jean choices for reference), so the results may not be as applicable to adults.

What does this mean for dieting?

We evolved as social creatures who wanted to be accepted by the tribe (lest you be cast aside to be eaten by some dinosaurs). Humans thrive on acceptance and approval, and dietary behaviour is no exception.

If you think losing weight will make you more desirable and successful, you are more likely to do it. And society is very good at delineating what is acceptable in terms of body image. It’s the washboard abs and massive glutes that get the Gymshark contracts. The red flags with massive delts that get the girl.

You want to be skinnier, so you drink “fat-burning” tea. You want a “detox” so you go on a juice cleanse. On some level, you know they don’t work. But, you believe being leaner means happier so you are willing to give it a go. This is well-evidenced in literature. Our beliefs and attitude to foods influence our consumption far more than our nutritional knowledge, or lack of[6].

I can fully attest to this. When I was doing my Leaving Certificate, I wanted to be as skinny as possible for my Sixth Year Holiday. The omniscient MyFitnessPal told me to eat 1,200 calories a day. I was six foot, eighteen, playing GAA three times a week, and running the other four. And yet I was only eating 1,200 calories. I knew on some level this was wrong, and that I shouldn’t be ravenous all the time. But, my attitudes to food and my body overrode my knowledge. If you hate the way you look, you will try almost anything if you believe you will be different.

So, what it means for us is that we really need to examine our thought process behind our beliefs, challenge them and be willing to change based on new information.

Self-Efficacy vs Self-Control

Self-control is limited, and also heavily influenced by our environment. Self-efficacy is slightly different. Self-efficacy refers to an individual’s belief in their ability to perform a task or in a certain situation[7]. It can be likened to self-confidence or self-esteem. Similar to self-control, the harder a task is, the less self-efficacy we have. We are then less likely to carry out the task[7].

Self-efficacy is linked to self-control. Indeed, studies have shown that self-efficacy is impaired following depletion of self-control[8].

What does this mean for dieting?

If you can’t consistently maintain self-control, your self-efficacy will be affected. You may find this loss of control correlating with negative thoughts about yourself and your body. You may not believe in your ability to lose weight and to change.

At its core – a poorly set-up training and nutrition plan that pushes you too much too soon can corrode your self-worth. It will demand too much of your mental space and time, and then when you eventually “crack”, you now have the addition of feeling like a failure!

You have finite mental space for dieting. The more of your energy you waste saying “I can’t”, fighting your own internal screaming telling you that kale smoothies are no way to live (correct), the less energy you have to succeed.

It doesn’t have to be awful all the time. Do yourself a favour and please do not embark on a detox or crash diet on January 1st. You deserve better than that.


  1. Baumeister, R.F., Vobs, K.D., Tice, D.M. (2017) ‘The Strength Model of Self-Control’, Current Directions in Psychological Science, 16(6), pp. 351-355. Available at: (Accessed 20 December 2020).
  2. Hagger, M., Wood, C., Stiff, C., Chatzisarantis, N.L. (2010) ‘Ego Depletion and the Strength Model of Self-Control: A Meta-Analysis’, Psychological Bulletin, 136(4), pp/ 495-525. Available at: (Accessed 21 December 2020).
  3. Finkel, E.J., Dalton, A.N., Campbell, W.K., Brunell, A.B., Scarbeck, S.J., Chartrand, T. L. (2006) ‘High-maintenance interaction: Inefficient social coordination impairs self-regulation’, Journal of Personality and Social Psychology, 91, pp. 456–475. Available at: (Accessed 21 December 2020).
  4. Silverman, B.G., Hanrahan, N., Huang, L., Rabinowitz, E.F., Lim, S. (2016) ‘Chapter 7 – Artificial Intelligence and Human Behaviour Modeling and Simulation for Mental Health Conditions’, Artificial Intelligence in Behavioural and Mental Health Care, 2016, pp. 163-183. Available at: (Accessed 21 December 2020).
  5. Hackman, C.L., Knowlden, A.P. (2014) ‘Theory of reasoned action and theory of planned behavior-based dietary interventions in adolescents and young adults: a systematic review’, Adolescent Health, Medicine and Therapeutics, 5, pp. 101-114. Available at: (Accessed 21 December 2020).
  6. Shepherd, R., Towler, G. (2007) ‘Nutrition knowledge, attitudes and fat intake: application of the theory of reasoned action’, Journal of Human Nutrition and Dietetics: The Official Journal of the British Dietetic Association, 20(3), pp. 159-169. Available at: (Accessed 21 December 2020).
  7. Yang, C., Zhou, Y., Cao, Q., Xia, M., An, J. (2019) ‘The Relationship Between Self-Control and Self-Efficacy Among Patient With Substance Use Disorders: Resilience and Self-Esteem as Mediators’, Frontiers in Psychiatry, 10, p. 388. Available at: (Accessed 21 December 2020).
  8. Graham, J.D., Bray, S.R. (2015) ‘Self-Control Strength Depletion Reduces Self-Efficacy and Impairs Exercise Performance’, Journal of Sport & Exercise Psychology, 37(5), pp. 477-488. Available at: (Accessed 21 December 2020).

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