Should You Add Cardio or Lift Weights on Keto
The ketogenic diet shifts your body’s primary fuel source from carbohydrates to fats, altering how you might approach exercise. While many focus solely on dietary changes, integrating the right type of physical activity can enhance fat loss and metabolic flexibility. This article examines the evidence behind cardio versus resistance training in a low-carb context.
How Ketosis Affects Exercise Performance
During the initial weeks of keto adaptation, endurance athletes often report reduced performance as their muscles transition to burning fat. A 2013 study in the British Journal of Nutrition found that very-low-carbohydrate diets initially decrease high-intensity exercise capacity but improve fat oxidation rates over time (Bueno et al., 2013). This explains why marathon runners may struggle with sprints early on but later develop superior endurance. the keto adaptation timeline details this process further.
Cardio on Keto: Steady-State vs HIIT
Steady-state cardio (like brisk walking or cycling) aligns well with keto, as fat oxidation supplies most of the energy. Tesco sells £8 heart rate monitors that help maintain the optimal fat-burning zone (60-70% of max heart rate). In contrast, high-intensity interval training (HIIT) relies more on glycogen, which remains limited on keto. However, research suggests HIIT may still benefit those fully fat-adapted by preserving muscle mass.
Weight Training and Muscle Preservation
Resistance training becomes particularly valuable on keto. A 2019 study in Frontiers in Endocrinology demonstrated that nutritional ketosis combined with strength training helped maintain lean mass during weight loss (Athinarayanan et al., 2019). Compound lifts like squats and deadlifts trigger muscle protein synthesis without demanding glycogen stores. Many UK gyms, including PureGym and The Gym Group, offer £20-£25 monthly memberships with free weights.
What This Means in Practice
For fat loss: Combine 2-3 weekly strength sessions with 150 minutes of moderate cardio (e.g., swimming at your local pool or walking in one of London’s many parks). In winter, indoor rowing machines (£200-£400 at Argos) provide a weather-proof option. Prioritise protein intake (1.6-2.2g per kg of body weight daily) to support muscle repair.
Frequently Asked Questions
Can I do both cardio and weights on keto?
Yes. Schedule them on separate days or perform cardio after weights to avoid compromising strength performance. Allow at least six hours between sessions for recovery.
Will keto make me weaker at lifting?
Initially, yes, as your body adapts. Most regain their strength within 4-6 weeks while becoming more efficient at burning fat during workouts.
How soon after starting keto can I exercise?
Begin with light activity in the first week (walking, yoga). Gradually reintroduce intense training as energy levels stabilise, typically by week 3-4.
The Bottom Line
Both cardio and resistance training have distinct roles in a ketogenic lifestyle. Cardio supports fat oxidation and cardiovascular health, while weight training preserves lean mass – crucial for maintaining metabolic rate during calorie restriction. Your ideal mix depends on goals: more weights for body composition, more cardio for pure fat loss. If you’d rather not do the macro maths yourself, the Keto Dieting app does it for you on Google Play and the App Store.
References
- Bueno NB, de Melo IS, de Oliveira SL, da Rocha Ataide T (2013). Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. British Journal of Nutrition. https://doi.org/10.1017/S0007114513000548
- Athinarayanan SJ, Adams RN, Hallberg SJ, et al. (2019). Long-Term Effects of a Novel Continuous Remote Care Intervention Including Nutritional Ketosis for the Management of Type 2 Diabetes: A 2-Year Non-randomized Clinical Trial. Frontiers in Endocrinology. https://doi.org/10.3389/fendo.2019.00348
