In Part 1 of this article, I discussed the components of a milk-based protein and the benefits of Whey protein. However, Whey protein might have some negative side effects as well…

Potential whey protein side effects

In general there are very few (if any) dangers involved in taking whey protein.

As stated in “The Essentials of Sport and Exercise Nutrition” by Dr John Berardi and Ryan Andrews [10] most of the fears regarding whey protein supplementation in healthy individuals are unsubstantiated.

“In the past, some have questioned the safety of higher protein intakes, as individuals with renal (kidney) disease and failure experienced a worsening of function when eating a higher protein diet. However, research has shown that in those with healthy kidneys, higher protein intakes present no renal stress and are quite well tolerated. Concerns about calcium loss are unsubstantiated. Within reason, higher protein intakes appear to have no negative consequences.”

But it should be stressed that taking whey protein shakes will never be as effective as getting your protein from whole foods. This is because whilst the shakes are convenient they will lack certain nutrients and minerals that are naturally found in food.

The long term effects

An issue that is affecting more and more people (due to the belief that protein is king) is the long term effects of exceeding their daily protein levels. As stated before, healthy individuals are unlikely to be affected by higher protein intakes. whey protein side effects_2But for those who are consuming double what they should, the risk of high blood pressure, kidney complications and heart disease can become a risk. You would have to be consuming very high amounts though!

Other issues that can occur, weight gain (if over-consumed, protein shakes average around 150-200 cals per shake) and for some people there is the risk of developing an unhealthy relationship with food. For example, taking protein shakes instead of food to control calories.

How to pick the right protein powder

First things first, check the protein level per serving. You want to be hitting at least 25g per serving. You might notice that there are different types on offer – Concentrates, Isolate and Hydrolysates.

I wouldn’t worry too much about which one to get of these as, in my opinion, there isn’t going to be much difference in terms of your results.

If you are looking to get bigger then a mass gaining protein powder might suit you (but you do run the risk of gaining body fat as well – they are high calorie) otherwise I would stick to a low fat/low carb protein powder.

Also, avoid whey protein mixed with Creatine, not because Creatine sucks (in fact it’s my favourite supplement) but because Creatine is really cheap and should be bought separately to save money!

Finally, I would choose Whey protein over Casein protein as studies indicate that Whey outperforms Casein in terms of muscle building {11][12]


To get the most out of whey protein, only use it when a whole food protein choice is unavailable or inconvenient. Track your daily calories and make sure that your protein shakes are not pushing your calories too high which would lead to unwanted weight-gain.

Make sure you are buying good quality whey protein powder that is suited to your goals.

And don’t stress out about the side effects, so long as you aren’t lactose-intolerant (it’s made out of milk after all) and don’t have any kidney problems whey protein is completely safe.

Finally, if you are caught short and don’t have any protein powder available then low fat chocolate milk is a fantastic replacement!

Connect with Expert Matthew Smith


[1] Hoffman, J., Falvo, M. 2004. Protein – Which is best? Journal of Sports Science and Medicine 3: 118-130

[2] Fulgoni, V. 2008 Current Protein Intake in America: analysis of the National Health and Nutrition Examination Survey, 2003-2004. American Survey for Clinical Nutrition 87(5): 15545-15575

[3] Naclerio, F., Alkhatib, A., Jiminez, A. 2013. Effectiveness of Whey Protein Supplement in Resistance Trained Individuals. Journal Sports Medicine & Doping Studies 3(3): 1-7

[4] Rankin, J., Goldman, L., Puglisi, M., Nickols-Richardson, S., Earthman, C., Gwazdauskas, F. 2004. Effect of post-exercise supplement consumption on adaptations to resistance training. Journal of the American College of Nutrition 23(4): 322-30

[5] Zhou, L., Xu, J., Rao, C., Han, S., Wan, Z., Qin, L. 2015. Effect of whey supplementation on circulating C-reactive protein. a meta-analysis of randomized controlled trials. Nutrients 7(2): 1131-1143

[6] Pal, S., Ellis, V. 2010 The chronic effects of whey proteins on blood pressure, vascular function, and inflammatory markers in overweight individuals. Obesity 18(7): 1354-9

[7] Daly, J., Reynolds, J., Sigal, R., Shou, J., Liberman, M. 1990. Effect of dietary protein and amino acids on immune function. Critical Care Medicine 18(2 Suppl): S86-93

[8] Hulmi, J., Laakso, M., Mero, A., Hakkinen, K., Ahtiainen, J., Peltonen, H. 2015. The effects of whey protein with or without carbohydrates on resistance training adaptations. Journal of the International Society of Sports Nutrition 16(12): 48

[9] Ma, J., Stevens, J., Cukier, K., Maddox, A., Wishart, J., Jones, K., Clifton, P., Horowitz, M., Rayner, C. 2009 Effects of a protein preload on gastric emptying, glycemia, and gut hormones after a carbohydrate meal in diet-controlled type 2 diabetes. Diabetes Care 32(9): 1600-2

[10] Berardi, J., Andrews, R. 2013. The Essentials of Sport and Exercise Nutrition 2nd ed. Precision Nutrition, Inc. p165

[11] Pennings, B., Boirie, Y., Senden, J., Gijsen, A., Kuipers, H., Van Loon, L. 2011 Whey protein stimulates postprandial muscle protein accretion more effectively than do casein and casein hydrolysate in older men. The American Journal of Clinical Nutrition 93(5):997-1005

[12] Tang, J., Moore, D., Kujibida, G., Tarnopolski, M., Phillips, S. 2009 Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. Journal of Applied Physiology 107(3): 987-92 

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