New Year’s Resolution Deja vu - Weight Loss
“This year I am going to lose weight and get into shape!”
Sound familiar? This phrase will carry a strong sense of déjà vu for many of us, especially soon after the start of a New Year. We are all aware of the numerous health benefits of maintaining a healthy weight, but the task itself can be daunting. We are inundated with advertisements, Facebook posts, or magazines suggesting new diets or exercise programs, which they claim will help you lose weight.
Awareness of obesity as an international health problem grew in the 1970’s, and recommendations were released suggesting that a low-fat diet was the scientifically proven way to achieve weight loss. This became a strong narrative which persists even today, despite growing evidence for many years that it is not necessarily true. In fact, a 2015 review of the actual scientific research from the 1970’s found that a low-fat diet was not actually being recommended at all! 1
So, what does the best available research actually tell us? How do we get rid of the extra kilograms and keep them off? Should we diet? Which diet is best? Should we exercise? Do we need to do both? Of course, it is complex, but let’s try and summarise the key points:
Which diet is best for losing weight?
This is a highly contentious topic, and it can be extremely difficult to pick out the facts from the fads. Should I be eating low fat? Maybe low carb? Perhaps high protein will be more effective?
The short answer is there is very little difference between diets. The keys are to keep your diet essentially balanced, and then to stick with whichever diet you choose. For short-term weight-loss there is some evidence that a low carb, high protein diet may be more effective 4, 5, 6, 7, 8. To decrease bad cholesterol and improve insulin sensitivity (decreasing the risk of Type 2 Diabetes), our diet should include unsaturated fats instead of saturated fats 9.
Diet or Exercise?
If I want to lose weight should I start a healthy diet or a new exercise program? There are limited high quality systematic reviews comparing the effects of exercise and diet. However, the evidence suggests that:
· For short and medium-term weight loss, diet may be more effective than exercise 2, 3.
· Exercise alone is not as effective as diet alone, or diet and exercise combined 2, 3.
· A combination of diet and resistance exercise (lifting weights) is best for losing weight and keeping it off for the long term 2, 3.
What else can I do?
Research shows that weight-loss aids such as behavioural interventions 10, meal replacements and anti-obesity drugs may also be helpful, especially for maintaining weight-loss 11.
1. Harcombe, Z., Baker, J. S., Cooper, S. M., Davies, B., Sculthorpe, N., DiNicolantonio, J. J., & Grace, F. (2015). Evidence from randomised controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis. Open heart, 2(1), e000196.
2. Johns, D. J., Hartmann-Boyce, J., Jebb, S. A., & Aveyard, P. (2014). Diet or exercise interventions vs combined behavioral weight management programs: a systematic review and meta-analysis of direct comparisons. Journal of the Academy of Nutrition and Dietetics, 114(10), 1557-1568.
3. Nicklas, B. J., Chmelo, E., Delbono, O., Carr, J. J., Lyles, M. F., & Marsh, A. P. (2015). Effects of resistance training with and without caloric restriction on physical function and mobility in overweight and obese older adults: a randomized controlled trial–. The American journal of clinical nutrition, 101(5), 991-999.
4. Tobias, D. K., Chen, M., Manson, J. E., Ludwig, D. S., Willett, W., & Hu, F. B. (2015). Effect of low-fat diet interventions versus other diet interventions on long-term weight change in adults: a systematic review and meta-analysis. The lancet Diabetes & endocrinology, 3(12), 968-979.
5. Clifton, P. M., Condo, D., & Keogh, J. B. (2014). Long term weight maintenance after advice to consume low carbohydrate, higher protein diets–a systematic review and meta analysis. Nutrition, metabolism and cardiovascular diseases, 24(3), 224-235.
6. Johnston, B. C., Kanters, S., Bandayrel, K., Wu, P., Naji, F., Siemieniuk, R. A., ... & Jansen, J. P. (2014). Comparison of weight loss among named diet programs in overweight and obese adults: a meta-analysis. Jama, 312(9), 923-933.
7. Naude, C. E., Schoonees, A., Senekal, M., Young, T., Garner, P., & Volmink, J. (2014). Low carbohydrate versus isoenergetic balanced diets for reducing weight and cardiovascular risk: a systematic review and meta-analysis. PloS one, 9(7), e100652.
8. Schwingshackl, L., & Hoffmann, G. (2013). Long-term effects of low-fat diets either low or high in protein on cardiovascular and metabolic risk factors: a systematic review and meta-analysis. Nutrition journal, 12(1), 48.
9. Schwab, U., Lauritzen, L., Tholstrup, T., Haldorsson, T. I., Riserus, U., Uusitupa, M., & Becker, W. (2014). Effect of the amount and type of dietary fat on cardiometabolic risk factors and risk of developing type 2 diabetes, cardiovascular diseases, and cancer: a systematic review. Food & nutrition research, 58(1), 25145.
10. Dombrowski, S. U., Knittle, K., Avenell, A., Araujo-Soares, V., & Sniehotta, F. F. (2014). Long term maintenance of weight loss with non-surgical interventions in obese adults: systematic review and meta-analyses of randomised controlled trials. Bmj, 348, g2646.
11. Johansson, K., Neovius, M., & Hemmingsson, E. (2013). Effects of anti-obesity drugs, diet, and exercise on weight-loss maintenance after a very-low-calorie diet or low-calorie diet: a systematic review and meta-analysis of randomized controlled trials–. The American journal of clinical nutrition, 99(1), 14-23.