Using Psychology to help
with your weight loss journey
How to Use the Theory of Planned Behaviour to Achieve Health and Weight Loss Goals
When it comes to achieving lasting health and weight loss results, motivation alone isn’t enough. To truly understand why some people succeed while others struggle—even when they want to change—we need to look at the psychology behind behaviour. One of the most effective and practical models for this is the Theory of Planned Behaviour (TPB).
What is the Theory of Planned Behaviour?
Developed by psychologist Icek Ajzen in 1991, TPB is a simple but powerful framework that helps explain why we behave the way we do. It suggests that three main factors influence our decisions and actions:
Attitude toward the behaviour – What are your beliefs about the outcome? Do you view the behaviour as positive and beneficial?
Subjective norms – How do the people around you influence your behaviour? Are you supported by your community, family, or peers?
Perceived behavioural control – Do you feel confident in your ability to take action and stick with it?
Together, these elements can predict whether someone will follow through with health-related goals, such as improving their diet, increasing physical activity, or making time for self-care.
Applying TPB to Health and Weight Loss
Let’s explore how you can apply this model in real life to create sustainable change:
1. Shift Your Attitude: Focus on Positivity and Purpose
If you want to change a health behaviour, you must genuinely believe it’s worth it.
Implementation ideas:
Create a “Why” Statement
Build a vision board
Use daily affirmations
2. Build Supportive Social Norms: Surround Yourself with Encouragement
Your social environment can strongly influence your choices.
Implementation ideas:
Partner with an accountability buddy
Curate your online influences
Communicate your goals with loved ones
3. Enhance Your Perceived Behavioural Control: Build Confidence Through Action
Confidence grows with small, achievable steps.
Implementation ideas:
Use SMART goals
Plan meals and workouts in advance
Learn new skills like batch cooking or guided breathwork
Weekly Activities to Reinforce TPB
| Activity | Purpose | TPB Construct Supported |
|---|---|---|
| Reflective journaling on health wins and goals | Strengthen belief in positive outcomes | Attitude |
| Group walks or fitness classes | Increase social support and accountability | Subjective Norm |
| Practicing a new healthy recipe weekly | Boost confidence through small wins | Perceived Behavioural Control |
| Creating habit trackers | Measure and visualise consistency | Perceived Behavioural Control |
| Sharing goals with a coach or mentor | Reinforce motivation through public commitment | Subjective Norm |
Work With Me: Personalised Support for Lasting Behaviour Change
Understanding a theory is powerful—but personalising it to your life and body is where the real magic happens. In my private naturopathic consultations and health coaching sessions, we explore your unique mindset, habits, and health goals through the lens of the Theory of Planned Behaviour. Together, we’ll:
Uncover hidden beliefs that may be holding you back
Strengthen your support systems (yes, even if you’re doing this alone!)
Build practical tools and strategies to help you feel in control of your health journey
Whether you’re working on weight loss, energy, hormones, or metabolic health, we’ll create a plan that aligns with both your goals and your lifestyle—without the overwhelm or guesswork.
👉 Ready to dive deeper?
Book your one-on-one consultation or health coaching session today and let’s put the science of behaviour change into action—so you can start feeling your best, from the inside out.
www.christinamathewson.com/appointments