What Does Evidence-Based Fitness Look Like? – James Krieger

Weight loss is a commonly held goal for many individuals.  To lose weight, caloric expenditure must exceed caloric intake. But, what makes the greatest impact on calories expended? Evidence-Based fitness helps us understand the role of non-exercise activity thermogenesis (NEAT) in weight management.

 

 

 

James Krieger – “The Statistics Guy”

 

 

James Krieger was one of four speakers that presented at the PTC conference.  Krieger is a well respected researcher, speaker and scientist in evidenced-based fitness, specialising in the area of weight management.  Krieger holds two Master’s degrees, one in Nutrition from the University of Florida, the other in Exercise Science from Washington State University.  He is a licensed nutritionist and the former head of research for weight-loss and obesity management for Microsoft.

 

 

On Day 1 of the conference, Krieger spoke about weight management and the critical role of non-exercise activity thermogenesis (NEAT) in weight loss.  In personal training, it is evident that many clients share the objective of weight loss.  As a pre-requisite for achieving this goal, it is imperative to understand that, in healthy adults, weight gain occurs when energy intake persistently exceeds energy expenditure [3].  The knowledge that increasing daily NEAT can directly mitigate the effects of increased calorie consumption and greatly contribute to weight loss is highly applicable for personal trainers and their clients.

 

 

What is NEAT?

 

 

NEAT is the energy expenditure of all physical activities outside that of volitional sporting-like exercise, sleeping or eating [1].  NEAT does not encompass going to the gym for a workout, but rather includes all activities of daily living including walking, climbing stairs, typing, fidgeting, muscle tone, and maintenance of posture [1].  NEAT may be easier to conceptualise by considering all movements to activities during work and leisure hours [1].

 

 

What is the Daily Energy Expenditure of NEAT?

 

 

In sedentary individuals, daily energy expenditure is approximately 15% [2].  In physically active individuals, total daily energy expenditure is approximately 50% or more [2].

 

 

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How Do We Measure NEAT?

 

 

Neat can be measured by one of two approaches:

 

1.  The first approach consists of measuring or estimating total NEAT.  Here, total energy expenditure is estimated, then from it, basal metabolic rate (BMR) plus thermic effect of food (TEF) is subtracted [2].

 

2.  The second approach is a factorial approach, whereby the components of NEAT are quantified, and the total NEAT is calculating by summing up these components [2].

 

  • BMR is energy expended when lying at complete rest.  It is largely (80%) calculated using lean body mass  BMR = 25.3 x Lean Body Mass (kg) [5].
  • TEF is energy expenditure associated with digestion, absorption and storage of food and represents approximately 10-15% of total daily energy expenditure [2].

 

 

Issues with Measuring NEAT

 

 

There are a few issues which make measuring NEAT levels problematic.  First, the great variety of activities that encompass NEAT make it very challenging to define in terms of human energy expenditure [2].  Also, the time period of measurement needed to gain a representation of NEAT is not well understood. [2].  A measurement period of 7 days have been used to provide a representative assessment of NEAT for a given period (i.e. 3 or 4 months) [1].  However, this measurement period is only a rough estimation.

 

 

NEAT in Weight Loss

 

 

The variance of NEAT among people can be substantial with as much as a 2000 kcal per day difference in energy expenditure [1].  Leisure activities alone, such as yard work, house cleaning or cycling after work, has the potential to impact total daily energy expenditure (TDEE) by up to 1000 kcal per day [1].  However, the most variance in NEAT levels between people is related to occupational differences [1].   Physical Activity Levels (PAL) values are commonly used to represent NEAT and is calculated by dividing TDEE by BMR [2].   For example, an office worker that performs sedentary desk work with a PAL of 1.6 and changes occupation to work in landscaping with a PAL of 2.4 could increase NEAT levels by 1200 kcal per day [2].

 

 

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A study by Ravussin and colleagues (1986) demonstrated the high degree of variance in NEAT among individuals [4].  In this study, the authors confined 177 subjects (103 males, 74 females) individually to a constructed respiratory chamber [4].  The respiratory chamber was 3m long, 2.5m wide, and 2.5m high and furnished with a toilet, sink, sofa-bed, desk, char, table, television, radio and intercoms [4].  The chamber formed an open-circuit calorimeter where both oxygen consumption and carbon dioxide production of each subject could be continuously measured and fresh air could be continuously drawn through the chamber [4].

 

 

NEAT was assessed both by having subjects wear a wrist motion sensor and via motion sensors mounted in the chamber [4].  Each subject spent a total of 24-hours in the respiratory chamber [4].  The results showed that energy expenditure varied significantly in each individual from 138 to 685 kcal per day [4] and the variance in energy expenditure were due to variability in the degree of NEAT levels i.e. walking around within the chamber and fidgeting [4].

 

 

Interestingly, energy expenditure was greater among obese subjects at all times compared to those of thinner subjects [4].  This was due to the larger mass of active tissue and higher energy costs of NEAT among obese subjects [4].  The authors note that energy expenditure resulting from NEAT is “an important component in total 24-hour energy expenditure and therefore in energy balance” and, for recommendations of daily caloric needs, “more emphasis should be given to the level of general physical activity” [4].

 

 

In an attempt to understand the impact of NEAT on weight gain, Levine and colleagues (1999) measured changes in energy storage in individuals who were overfed for 8 weeks [3].  Sixteen non-obese adults (12 males and 4 females, 25 to 36 years of age) underwent measures of body composition and energy expenditure before and after 8 weeks of overfeeding 1000 kcal per day above their maintenance calories [3].  On average, subjects gained 4.7 kg over the 8 week study period and fat gains were the same in males in females [3].

 

 

The authors assessed basal metabolic rate and found that overfeeding increased BMR by an average of 5% accounting for 8% of the excess energy ingested [3].  Also, thermal effect of food was measured and found to increase by 14% with overfeeding, but did not correlate with fat gain [3].  Therefore, both BMR and TEF did not account for the large variability in fat gain among subjects [3].  Instead, the authors found NEAT to be the primary mediator of weight gain with overfeeding [3].

 

 

The average increase in NEAT (336 kcal per day) accounted for two-thirds of the increase in daily energy expenditure [3].  Changes in NEAT accounted for a 10-fold difference in fat storage that predicated resistance to fat gain with overeating.  Lower values of NEAT correlated with the greatest weight gain, while those with higher NEAT were able to dissipate the excess energy so that excess calories were not stored as fat [3].  The graph below (Graph C) show the linear correlation between increased fat gain (kg) and decreased NEAT levels [3].

 

 

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What Did I Learn? – Practical Application For Our Clients

 

 

With the great majority of personal training clients sharing the goal of weight loss, understanding areas that directly impact weight gain and weight loss are crucial to facilitating a pathway toward this objective.  In addressing the goal of weight loss, personal training focusses principally on progressive resistance and proper nutrition.  While addressing both these areas will make positive contributions to a clients weight loss, assessing NEAT will undoubtably contribute the most to increasing daily caloric expenditure.

 

 

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More recently, the media have popularised the recommendation of achieving 10,000 steps per day as a marker for adequate general activity with expected health benefits.  This recommendation can be traced back to Japanese walking clubs and made popular by pedometer manufacturers [7].  However, presently, there is lack of direct evidence that accumulating  any number of steps/day is associate with weight loss or reduced mortality.  Although, previous studies have reported that 30 minutes of moderate physical activity (i.e. walking) equates to approximately 10,000 steps/day [7].

 

 

A study by Yamanouchi et al. (1995) showed that an exercise and diet group of individuals instructed to take 10,000 steps/day over a 6-8 week period lost an average of 7.7 kg (3.6 kg more than a control group averaging 4,000 steps/day) [8].  Although, the subjects in this study exceeded the set goal averaging >19,000 steps/day [8].  Still, normative data to date indicate that 10,000 steps is reasonable for healthy adults [6].  Although for low active populations, such as among the elderly and those living with chronic disease, incremental increases of 2,000 – 2,500 steps/day above 10,000 steps/day is recommended [6].

 

 

Many strategies for personal trainers exist to help promote increasing client NEAT levels.  Those include, but are certainly not limited to:

 

  • Walk to work
  • Walk during lunch hour
  • Walk after dinner
  • Set up treadmill in front of TV
  • Take stairs instead of escalator or elevator
  • Park farther from destination
  • Walk to co-worker’s desk instead of emailing or calling them
  • Get off a stop early and walk
  • Walk the dog more frequently
  • Purchase a pedometer or accelerometer to set daily step goals

 

 

Educating clients on NEAT and the importance of maintaining adequate daily general movement for goals including weight loss are highly important and an essential component of our personal training service.  In assessing NEAT, we use pedometers with our clients as a simple, yet effective, method for gathering information related to daily, general movement.  This information is then utilised in combination with structured exercise and nutrition to accelerate the process of goal achievement.

 

 

If you would like to learn more about our personal training and approach to evidence-based fitness here in Edinburgh, please click here to find out more about us.

 

 

 

References

 

 

1.  Levine, J. A. et al. 2006. Non-Exercise Activity Thermogenesis. The Crouching Tiger Hidden Dragon of Societal Weight Gain. Arteriosclerosis, Thrombosis, and Vascular Biology. April. Vol. 26, No. 4, pp. 729-736.

 

2.  Levine, J. A. 2004. Nonexercise activity thermogenesis (NEAT): environment and biology. American Journal of Physiology, Endocrinology and Metabolism. May. Vol. 285. No. 5. E675-685.

 

3.  Levine, J. A. et al. 1999. Role of Nonexercise Activity Thermogenesis in Resistance to Fat Gain in Humans. Science. January. Vol. 283, No. 5399, pp. 212-214.

 

4.  Ravussin, E. et al. 1986. Determinants of 24-hour energy expenditure in man. Methods and results using a respiratory chamber. The Journal of Clinical Investigation. December. Vol. 78, No. 6, pp. 1568-1578.

 

5.  Schuler, L. & Aragon, A. 2014. The Lean Muscle Diet. Rodale Inc. New York.

 

6.  Tudor-Locke, C. et al. 2011. How many steps/day are enough? For adults.  The International Journal of Behavioural Nutrition and Physical Activity. July. Vol. 8, No. 79, pp.1186/1479-5868-8-79.

 

7.  Tudor-Locke, C. & Bassett DR Jr. 2004. How many steps/day are enough? Preliminary pedometer indices for public health. Sports Medicine. Vol. 34, No. 1, pp.1-8.

 

8.  Yamanouchi K et al. (1995). Daily walking combined with diet therapy is a useful means for obese NIDDM patients not only to reduce body weight but also to improve insulin sensitivity. Diabetes Care. Vol. 18, No. 6, pp. 775-778.

 

 

 

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