High-fat Overfeeding, Hepatokines and Appetite Regulation (OVEREAT)

Influence of High-fat Overfeeding on Circulating Hepatokine Concentrations: a Randomised Crossover Study

The present study will investigate the effect of high-fat overfeeding on a group of liver-secreted proteins linked to worsened blood sugar control, as well as proteins involved in appetite control. Participants will consume both a high-fat diet, consisting of 50% extra calories above their daily required intake, and a control diet, consisting of their normal 'habitual' diet, with each diet lasting seven days. The diets will be undertaken in a randomised order, with a period of three weeks separating the two diets. Blood samples will be taken before and after each diet to measure blood sugar control. Further blood samples will also be taken 24 hours and 72 hours into each diet to see how levels of the liver and appetite-regulating proteins change over the course of the seven days. It is expected that blood sugar control will be worsened by the high-fat diet and this will be accompanied by increases in levels of the liver-secreted proteins and an impaired release of the appetite-regulating proteins into the blood.

In recent years, researchers have identified a number of liver-secreted proteins, termed "hepatokines", which are thought to play an important role in inter-organ crosstalk between the liver and other metabolically active tissues such as skeletal muscle and adipose tissue. Specifically, previous studies have demonstrated that hepatokines contribute to whole body glucose and lipid homeostasis through acting in an endocrine-like fashion. Understanding how circulating concentrations of these hepatokines can be manipulated in humans is essential, as impaired blood glucose and lipid control is a key feature of metabolic diseases, such as type 2 diabetes and non-alcoholic fatty liver disease. Previous research at Loughborough University has found that acute high-fat overfeeding for up to seven days can impair glycaemic control; however, the exact mechanisms responsible for these detrimental changes are not fully understood. Based upon previous evidence that hepatokine production is nutritionally modulated, the investigators believe that changes in hepatokine production may play a role in the detrimental metabolic effects seen following short-term, high-fat overfeeding which has implications for long-term metabolic health. Appetite regulation is also thought to play a role in the pathophysiology of obesity and insulin resistance, as the impaired secretion of several appetite regulatory hormones in both fasting and postprandial conditions has been observed in obesity, which is characterised by an chronic excessive energy intake. Therefore, the investigators are also interested to examine the appetite regulatory hormone response to short-term, high-fat overfeeding. The present study is a randomised, controlled, crossover study in which twelve recreationally active, healthy males will consume both a hypercaloric, high-fat diet (consisting of 50% extra energy above the daily requirement, 65% of which is fat) and a control diet (the participants' habitual diet) in a randomised fashion. A three-week washout period will separate the two diets in order to remove any lasting effects confounding the subsequent diet. Following a prescreening session in which anthropometric data will be collected, participants will commence their first dietary condition. An oral glucose tolerance test will be performed before and after the two diets to measure changes in glycaemic control/whole body insulin sensitivity. Further blood samples will be taken 24 hours and 72 hours after commencing the diets in order to observe the time course of any changes in circulating hepatokine and appetite hormone concentrations. Physical activity will also be monitored for the duration of the two dietary conditions to ensure that habitual physical activity levels are maintained.

Hepatokines, High Fat Diet, Glycaemic Control, Fibroblast Growth Factor 21, Leukocyte Cell-derived Chemotaxin 2, Fetuin-A, Appetite, Ghrelin, Peptide YY

The study design is a randomised, controlled, crossover design in which participants undertake two 7-day dietary conditions in a randomised order with a three week washout period in between.

Participants will consume a hypercaloric, high-fat diet. Participants will be provided with all the food during the week and will be instructed to consume all of the foods provided and no extra calorie containing food or drink. In the event of leftover food, participants will be asked to return the food for measurement and subsequent subtraction from their total energy intake.

Participants will consume their normal 'habitual' diet for seven days which will be compared to their habitual diet recorded by a three day food diary before commencing the two diets. Participants will be instructed to carry on as normal and eat their usual diet and this period will be used as a comparator to the high-fat diet. They will also be told to record their food intake for 3 days during the diet to quantify their control diet.

The high-fat diet will provide 7 days of overfeeding comprising of: +50% extra calories above the daily required intake, 65% of which is fat.

Time-course of subjective ratings of hunger across the 7-day dietary interventions, measured using an appetite visual analogue scale. The scale is divided into subscales of different appetite perceptions including: hunger, fullness, satisfaction and prospective food consumption. Each subscale is rated on a 100mm scale (i.e. from 0 - 100), with a rating of 100 fully supporting the perception and a rating of 0 fully opposing the perception.

Time-course of subjective food preference across the 7-day dietary interventions, measured using the Leeds Food Preference Questionnaire.

Changes in whole-body insulin sensitivity using the Matsuda Index, calculated from plasma glucose and insulin concentrations during the oral glucose tolerance test

Changes in HOMA-IR (a marker of hepatic insulin resistance) using baseline concentrations of plasma glucose and insulin.

Changes in ADIPO-IR using baseline concentrations of plasma insulin and non-esterified free fatty acids.

Amounts of sitting time, standing time, light activity and moderate-vigorous activity will be measured across the duration of each diets to compare between the two. This will be Measured using Acitgraph and ActivPAL monitors.

Changes in resting metabolic rate in response to the diets will be measured using indirect calorimetry and estimated using the Haldane transformation.

Changes in fat oxidation in response to the diets will be measured using indirect calorimetry and estimated using the Haldane transformation.

Changes in blood pressure (systolic and diastolic) across the two dietary interventions will be measured using an automated pressure cuff.

Changes in body fat percentage across the two dietary interventions using bioelectrical impedance analysis.

Inclusion Criteria: Recreationally active - ≤ 2 structured exercise sessions per week BMI between 18.5 - 27.9 kg/m2 Body fat percentage < 20% Metabolically healthy - No known cardiovascular or metabolic disease such as diabetes, respiratory or heart disease. Non-smoker Weight stable in the past 6 months Normal fasting blood glucose levels (3.6 - 5.5 mmol/l) Exclusion Criteria: Contraindications to exercise Needle Phobia

Badman MK, Pissios P, Kennedy AR, Koukos G, Flier JS, Maratos-Flier E. Hepatic fibroblast growth factor 21 is regulated by PPARalpha and is a key mediator of hepatic lipid metabolism in ketotic states. Cell Metab. 2007 Jun;5(6):426-37. doi: 10.1016/j.cmet.2007.05.002.

Dasgupta S, Bhattacharya S, Biswas A, Majumdar SS, Mukhopadhyay S, Ray S, Bhattacharya S. NF-kappaB mediates lipid-induced fetuin-A expression in hepatocytes that impairs adipocyte function effecting insulin resistance. Biochem J. 2010 Aug 1;429(3):451-62. doi: 10.1042/BJ20100330.

Groop LC. Insulin resistance: the fundamental trigger of type 2 diabetes. Diabetes Obes Metab. 1999 May;1 Suppl 1:S1-7. doi: 10.1046/j.1463-1326.1999.0010s1001.x.

Hulston CJ, Churnside AA, Venables MC. Probiotic supplementation prevents high-fat, overfeeding-induced insulin resistance in human subjects. Br J Nutr. 2015 Feb 28;113(4):596-602. doi: 10.1017/S0007114514004097. Epub 2015 Jan 29.

Lan F, Misu H, Chikamoto K, Takayama H, Kikuchi A, Mohri K, Takata N, Hayashi H, Matsuzawa-Nagata N, Takeshita Y, Noda H, Matsumoto Y, Ota T, Nagano T, Nakagen M, Miyamoto K, Takatsuki K, Seo T, Iwayama K, Tokuyama K, Matsugo S, Tang H, Saito Y, Yamagoe S, Kaneko S, Takamura T. LECT2 functions as a hepatokine that links obesity to skeletal muscle insulin resistance. Diabetes. 2014 May;63(5):1649-64. doi: 10.2337/db13-0728. Epub 2014 Jan 29.

Meex RCR, Watt MJ. Hepatokines: linking nonalcoholic fatty liver disease and insulin resistance. Nat Rev Endocrinol. 2017 Sep;13(9):509-520. doi: 10.1038/nrendo.2017.56. Epub 2017 Jun 9.

Parry SA, Smith JR, Corbett TR, Woods RM, Hulston CJ. Short-term, high-fat overfeeding impairs glycaemic control but does not alter gut hormone responses to a mixed meal tolerance test in healthy, normal-weight individuals. Br J Nutr. 2017 Jan;117(1):48-55. doi: 10.1017/S0007114516004475. Epub 2017 Jan 24. Erratum In: Br J Nutr. 2017 Feb;117(4):622.

Uebanso T, Taketani Y, Yamamoto H, Amo K, Ominami H, Arai H, Takei Y, Masuda M, Tanimura A, Harada N, Yamanaka-Okumura H, Takeda E. Paradoxical regulation of human FGF21 by both fasting and feeding signals: is FGF21 a nutritional adaptation factor? PLoS One. 2011;6(8):e22976. doi: 10.1371/journal.pone.0022976. Epub 2011 Aug 1.

Lean ME, Malkova D. Altered gut and adipose tissue hormones in overweight and obese individuals: cause or consequence? Int J Obes (Lond). 2016 Apr;40(4):622-32. doi: 10.1038/ijo.2015.220. Epub 2015 Oct 26.

Willis SA, Sargeant JA, Yates T, Takamura T, Takayama H, Gupta V, Brittain E, Crawford J, Parry SA, Thackray AE, Varela-Mato V, Stensel DJ, Woods RM, Hulston CJ, Aithal GP, King JA. Acute Hyperenergetic, High-Fat Feeding Increases Circulating FGF21, LECT2, and Fetuin-A in Healthy Men. J Nutr. 2020 May 1;150(5):1076-1085. doi: 10.1093/jn/nxz333.