This is part two of two posts covering the conference. The first part which included the presentations on "fueling the brain", "carbohydrates for performance", and "train high, sleep low" is posted here.
These are my notes from the last three presentations of the day. Although there was a lot of valuable information shared, I've noted the things that were most interesting to me and that I thought were items that I could immediately implement in my own training and for the athletes I coach.
If you would like to see the presentations in full and also have access to the handouts and other resources they are available on mysportscienceacademy.com. I've found this platform very useful as I was able to go through the presentations again and capture any points I missed. There will also be future presentations and courses available that I'll be looking out for.
Protein and weight loss - Dr Stuart Phillips
Professor and Tier 1 CRC, Kinesiology McMaster University
Phillips presented on the need for higher dietary protein to maintain muscle mass and aid weight loss during a period of energy restriction. He presented a number of different studies that clearly supported his points and which were easy to understand. I found this approach to be practical and pragmatic and I appreciated how the topics of the studies were directly applicable to anyone reading them. Many of his studies were his own work which I highly recommend reading. I would also suggest following him on twitter (@mackinprof) as he regularly shares great content.
- The starting point, or ground rules, for the presentation were:
- all weight loss runs through energy balance (calories in vs calories out)
- there are no magic nutrients
- there is no specific diet that is better than another.
- There is a recommended range for macronutrients, the acceptable macronutrient density range (AMDR), which is:
- CHO 45-65%
- Fat 20-35%
- Protein 10-35%.
- Before discussing protein for weight loss, two myths about protein need to be dispelled:
- there is no data that links high protein diets to renal failure
- there is no data that high protein leads to acidification of the blood and calcium leaching.
- There are a number of very good reasons for increasing protein consumption during periods of weight loss:
- thermic effect
- poor substrate for lipogenisis
- reserving muscle mass
- protein is nutrient dense.
- When we lose weight, the weight is not only fat:
- fat mass is usually 70% of the weight
- bone loss can be 0.5-1% (therefore calcium and vitamin D suplementation may be necessary)
- muscle loss is usually 30%.
- However, increasing protein has been shown to reduce the negative aspects of weight loss:
- One of the best sources of protein is dairy:
- it is high in leucine (whey and caseine are two good sources)
- it is nutrient dense which is critical when consuming a energy restrictive diet
- the IDEAL trial showed that high dietary protein, in particular dairy, resulted in improved composition of weight loss.
- Under extreme calorie deficits, a higher protein diet combined with intense exercise promoted greater lean mass gain and greater fat mass loss. This study was absolutely fascinating and very informative for anyone trying to lose weight quickly without compromising skeletal muscle:
- 4-week long study with a 40% energy deficit (40%!)
- participants performed resistance training and high intensity interval training 6 times a week
- CHO was held at 3g/kg/day
- a high protein group at 2.4g/kg/day was compared to a lower protein group at 1.2g/kg/day
- the results showed that a higher protein diet during a calorie deficit was more effective at promoting gains in lean body mass and losses of fat when combined with high intenstity training.
My summary and practical steps
- Protein is critical for maintaining skeletal muscle while in a calorie deficit.
- A higher protein diet is not dangerous and actually helps both fat loss and maintainance of lean body mass.
- A protein intake of 2.4g/kg/day is a significant amount of protein requiring protein at each meal.
- Dairy is an excellent source of leucine and a great option for meeting higher protein diet requirements.
The latest on nitrates - Dr Andrew Jones
Professor of Applied Physiology & Assistant Deputy Vice-Chancellor University of Exeter
Jones presented an update on the latest research on nitrates. He is an authority on nitrates and their impact on sports performance so it was fascinating to hear his latest thoughts and assessment of the research that is currently taking place. In particular, I found the studies he presented about nitrates stored in the skeletal muscle and the possibility of nitrate loading before an event to be new and something I had not considered before. You can find out more about him including all his publications here. He also shares extensively on twitter under the appropriate username of @AndyBeetroot.
- Why is nitric oxide (NO) important? It is involved in the control of:
- vascular tone, blood flow
- mitochondrial respiration
- muscle excitation-contraction coupling
- glucose homeostasis
- immune function.
- There are two pathways for NO synthesis:
- L-arginine + O2 --> NOS --> NO
- Nitrate (NO3) --> Nitrite (NO2) --> NO.
- There are multiple sources of nitrate, mostly from leafy green vegetables.
- Most dietary sources are not concentrated enough for benefit, beet juice concentrate is needed with nitrate concentration of 6-10mmol.
- The rate at which ingested nitrate or nitrite makes it into the blood plasma differs:
- nitrate = 2-3 hours
- nitrite = 3-4 hours (as it needs to be converted to nitrate first).
- Bacteria in the mouth and micro-biome are critical in processing nitrates:
- careful with using mouthwash before taking nitrates as it may reduce the bio-activity and benefits of taking nitrates.
- Nitrates have shown to reduce the oxygen cost of exercise and increase time to exhaustion
- meta-analysis of 26 placebo-controlled randomised trials - nitrates significantly decrease VO2 during submaximal exercise (Pawlak-Chaouch et al)
- acute dietary nitrate supplementation improves cycling time trial performance (Lansley et al)
- meta-analysis of 76 trials for nitrate supplementation - exercise capacity and time trial performance improved (McMahon et al)
- aerobic fitness affects the exercise performance responses to nitrate supplementation - elite performers show lower response (Porcelli et al).
- Newer research has been concentrating on sprint performance (rather than looking at only endurance activities):
- nitrate supplementation appears to increase explosive force production, thereby increasing speed and power
- nitrate supplementation enhances the contractile properties of human skeletal muscle (Haider et al)
- acute dietary NO3 intake increases whole-body NO production and muscle speed and power (Coggan et al).
- More new research has been investigating if nitrites and nitrates are stored in skeletal muscle:
- skeletal muscle nitrate reservoir contributes significantly to the generation of nitrite and then exercise-induced functional hyperemia (Piknova et al)
- nitrate depleted from skeletal muscle during starvation is quickly recovered from new dietary sources, with an unexpected significant "overload" (Gilliard et al).
My summary and practical steps
- Nitrates are critical for multiple functions in the body and should be considered for use in sport to increase performance.
- Although most research has focused on endurance sports, there is new research suggesting that nitrates could be beneficial to sprint and power sports.
- Nitrates are stored in skeletal muscle and a depletion protocol and loading phase may produce the greatest benefits from taking nitrates before a race. This could be especially significant in elite performers who have a lower response to nitrate consumption.
Is breakfast the most important meal of the day? - Dr James Betts
Professor of Metabolic Physiology and editor-in-Chief of the International Journal of Sport Nutrition & Exercise Metabolism University of Bath
Betts presented his work (full list of publications available here) with the focus on his investigations into breakfast and its importance. This presentation felt like a myth-busting session as he presented a number of different studies that looked into the effects of skipping breakfast and the associated public perceptions of this. It's not clear whether or not breakfast is the most important meal of the day because it's nuanced and complicated and it depends on multiple factors. However, I found it useful to learn about the role of breakfast so I can make more informed decisions in the future.
- Managing of food consumption should ideally be synchronised with circadian rhythms and activity:
- Energy balance is key to weight loss (in accordance with Phillips above) and there are some compensatory factors when breakfast is skipped:
- the Bath Breakfast Project (Betts et al, 2016) showed that "even if net energy intake is reduced, extended morning fasting may not result in expected weight loss due to compensatory adjustments in physical activity thermogenesis"
- this was further researched and explored in another study by Betts - see below.
- What are the impacts of skipping breakfast?
- skipping breakfast did not significantly affect the amount of food consumed at lunch, only 50kCal additional were consumed (Chowdhury et al, 2016)
- skipping breakfast did not result in full compensation later in the day. After skipping a 700kCal breakfast, study participants only ate an additional 540kCal later in the day (Chowdhury et al, 2015)
- the resting metabolic rate appears to be the same between skipping or eating breakfast; i.e. eating breakfast does not increase the base metabolic rate
- diet-induced thermogenesis is a factor as breakfast eaters burned more calories, however, the calories burned were not enough to compensate for the additional calories consumed during breakfast
- physical activity thermogenesis was higher in breakfast eaters (Betts et al) especially in the morning. This appears to be a result of fidgeting and more general lifestyle movement in breakfast eaters.
- The body composition of the person skipping breakfast also makes a difference:
- in obese adults, daily breakfast leads to greater physical activity during the morning, whereas morning fasting results in partial dietary compensation (Chowdhury et al, 2016)
- in obese study participants "insulin sensitivity increased with breakfast relative to fasting" (Chowdhury et al, 2016)
- Gonzalez et al found that " reduced adipose glucose uptake in obesity is a physiological down-regulation to prevent excessive de novo lipogenesis".
My summary and practical steps
- Breakfast is not necessarily the most important meal of the day. It really depends on synchronising to circadian rhythms and also timing intake with activity.
- Skipping breakfast is not a big deal and is possibly a good method to reduce daily calories as the compensatory factors do not always match up to the amount of calories missed at breakfast.
- The biggest compensatory factor is physical activity thermogenesis, so if you are skipping breakfast and trying to lose weight then planning training in the morning to force physical activity may be a successful approach.
I've found that these speakers share a great deal of fantastic material on twitter. There are often links and studies that provide valuable insight into sports nutrition. If you're interested in following them, you can find all of them on my twitter list.