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Effects of Overnight Fasted Exercise on Weight Loss & Body Composition

Bob Lee & Cierra Mattern

Washington State University, Kinesiology 380

Systematic Review and Meta Analysis:

Examines effects of overnight-fasted exercise versus fed exercise on weight loss and body composition.

Body mass, body fat, lean body mass, fat-free mass

No supporting evidence that fasted or fed states of exercise are superior in weight loss/changes in body comp efforts (Hackett, & Hagstrom, A., 2017).

Comparative Studies:

Gillen J.B. (2013) study, showed no change in body composition in fed versus fasted states.

Sedentary obese women, HITT, Dexa scans

De Bock K (2008) study found data that fasted, more than fed, enhanced the contribution of IMCL (Intramyocellular lipid) to energy during exercise

Males, cardio, carbohydrate fed states, physically active

The above ⅖ studies from the review, further demonstrate the conflicting data and possible explanations for why.

Vieira A.F., (2016) meta analysis review on fat oxidation found that the fasted aerobic exercise group shows higher fat oxidation thus creating a larger negative net fat-balance.

Food is fuel, but what if ‘weight loss’ is more complicated than energy in/out?

Research aim: effects of overnight fasted exercise on different forms of weight loss and overall body composition.

PURPOSE:

OVERVIEW:

BACKGROUND:

Figure 5. Fasted vs Fed Exercise on weight loss & composition

● No significant differences were observed in weight loss and body composition.

● Hypocaloric diet > Exercise state (Fasted or Fed) for weight loss and body composition change.

There is still strong physiology theories for fasting and fasted exercise supported by some studies.

Remains unsolved question- suggest that further studies are required.

CONCLUSIONS:

Formal analysis to further improve methods/approaches to gain more narrowed results impact overnight fasting has.

(females vs males, protein vs COH, HITT vs cardio, low-intensity vs high intensity meeting a threshold,

IF found that overnight fasting=proportional to fat mass loss and positive changes in body composition:

Exercise prescription for obese patients.
Figure competitions & PT’s training.

APPLICATION:

1)Burke, L.M., (1999) Fueling strategies to optimize performance: training high or training low?” Scandinavian Journal of Medicine and Science in Sports, 20(2), 48–58, DOI: 10.1152/jappl.1999.86.2.479. PMID: 9931180

2)De Bock K., Derave W., Eijnde B.O., Hesselink M.K., Koninckx, E., Rose, A.J., Schrauwen P., Bonen, A., Richter E.A., Hespel P., (2008) Effect of training in the fasted state on metabolic responses during exercise with carbohydrate intake. Journal of Applied Physiology, 104(4), 1045–1055

3)Gillen J.B., Percival M.E., Ludzki, A., Tarnopolsky M.A., Gibala, M.J., (2013) Interval training in the fed or fasted state improves body composition and muscle oxidative capacity in overweight women. Obesity, 21, 2249–2255.

4)Gropper, S.S., Smith, J.L, (2012) Advanced Nutrition and Human Metabolism; Cengage Learning: Belmont, CA, USA.

5)Hackett & Hagstrom, A. (2017). Effect of Overnight Fasted Exercise on Weight Loss and Body Composition: A Systematic Review and Meta-Analysis. Journal of Functional Morphology and Kinesiology, 2(4), 43. https://doi.org/10.3390/jfmk2040043

6)Jeukendrup A.E., (2002) Regulation of fat metabolism in skeletal muscle. Annals of the New York Academy of Sciences, 967, 217–235

7)Schoenfeld B.J., Aragon A.A., Wilborn C.D., James W Krieger., Sonmez G.T., (2014) Body composition changes associated with fasted versus non-fasted aerobic exercise. Journal of International Society Sports of Nutrition, 54(11), https://doi.org/10.1186/s12970-014-0054-7

8)Vieira A.F., Costa, R.R., Macedo, R.C., Coconcelli, L., Kruel L.F., (2016) Effects of aerobic exercise performed in fasted v. Fed state on fat and carbohydrate metabolism in adults: A systematic review and meta-analysis. British Journal of Nutrition, 116, 1153–1164

Figure 2. Exercise Fat oxidation during exercise performed in Fasted vs Fed state (Vieira et al., 2016)

Figure 1. Fat Oxidation Rates vs VO2Max (Jeukendrup et al., 2002).

Figure 4. Fasted vs Fed in Fat mass and Lean mass (Gillen et al., 2013)

Lean Body Mass

Figure 3. Pre- vs. Post- Fasted & Fed: Body Comparison (Schoenfield et al., 2014)

Fat-free mass

(√)Hedges’ g value

In the last decade, fasting aerobic training has become a popular method for improving body composition. (Burke, 2010)

Overnight fasted exercise is considered as the most common type of fasted exercises. - 8 to 12 hours in fasted state (Hackett & Hagstrom., 2017)

Fat oxidation generates energy for bodily functions such as muscle contraction (Gropper et al., 2012).

Aerobic exercise increases fat oxidation and the capacity to oxidize fat (Jeukendrup et al., 2002).

Aerobic exercise in a fasted state induces higher fat oxidation than a fed state (Viera et al., 2016).

(Hackett & Hagstrom, 2017)