Increased Protein at Breakfast for Weight Management in Overweight Adolescents

Adolescent obesity continues to be a major public health concern due to the increased risk of
developing chronic diseases, including, but not limited to, type 2 diabetes. Thus, strategies
are vitally needed that target weight management and glycemic control to reverse the obesity
epidemic and prevent and/or delay serious health complications in young people. The daily
consumption of breakfast has been touted as an essential part of the diet to prevent and/or
treat obesity. While breakfast was once thought to be 'the most important meal of the day',
this notion has recently been challenged due to the paucity of existing causal evidence. In
addition, interest in the study of breakfast and weight management has highlighted the
importance of macronutrient content, particularly increased dietary protein at breakfast, as
a critical factor. Pilot data has illustrated reductions in body fat mass and improvements in
glycemic control following the daily consumption of high protein breakfasts over a short
period in overweight adolescents. However, it is unclear as to whether these effects would
occur over the long-term and what mechanisms-of-action contribute to the improvements in
these health outcomes. Aim 1 will determine whether a causal link exists between breakfast,
particularly one rich in dietary protein, and weight management in young people. To
accomplish this, 150 overweight, habitual breakfast-skipping adolescents will complete the
following long-term randomized, tightly-controlled breakfast trial. Participants will be
randomly provided with high protein breakfasts (350kcal; 34% protein (30g protein), 40% CHO,
and 26% fat); isocaloric normal protein breakfasts (350kcal; 11% protein (10g protein), 63%
CHO, and 26% fat); or will continue to skip breakfast for 6 mo. Baseline, 3, and 6 body
weight, body composition, and free-living glycemic control will be assessed. In addition,
daily intake, with particular focus on evening snacking behavior, will also be measured at
baseline, 3, and 6 mo. Aim 2 will identify the appetitive, hormonal, and neural signals by
which a protein breakfast modulates ingestive (i.e., eating) behavior and weight management.
To address this aim, a sub-set of the 150 (n=75) will complete 10-h testing days during
baseline, 3, and 6 mo. Repeated assessments of perceived appetite, satiety, and food cravings
along with appetite-regulating hormonal responses (i.e., plasma ghrelin, GLP-1, PYY, and HVA
(the primary dopamine metabolite)) will be measured throughout the day. In addition,
post-breakfast and pre-dinner functional (fMRI) brain scans will also be completed to
identify neural activation to food stimuli in cortico-limbic brain regions known to modulate
food motivation, reward, and cravings along with structural scans. Aim 3 will identify
specific appetitive, hormonal, and neural signals as strong predictors of ingestive behavior
and weight management. Within this sub-set of 150, aim 4 will determine whether a causal link
exists between breakfast, particularly one rich in dietary protein, and cognitive performance
(memory, attention, and executive function). These assessments will also be paired with
structural scans. The measures collected in Aim 2 will be analyzed in combination with food
choice, daily intake, weight loss, and reductions in body fat following the 6-mo
interventions. Collectively, this project will provide novel evidence testing the consumption
of a high protein breakfast as a dietary strategy to combat obesity in young people.

Inclusion Criteria:

- All ethnicities

- BMI: 25-34kg/m2 or 85th-98th percentile

- Skips Breakfast (<110 kcal prior to 10 am) at least 4 days/week for the past year

- Never smoked or used other tobacco products

- Willing to consume the study breakfasts

- Generally healthy

Exclusion Criteria:

- Clinically diagnosed with an eating disorder

- Metabolic, hormonal, and/or neural conditions/diseases that influence metabolism or
appetite

- Currently or previously on a weight loss or other special diet (in the past 6 months)

- Gained/lost ≥4.5kg over the past 6 months

- Taking medication that would directly influence appetite (weight-loss drugs or
antidepressant, steroid, or thyroid medication, unless dosage has been stable for at
least 6 months)

- Normal cognitive restraint (assessed from the Three Factor Eating Habits
Questionnaire)

- Does not consistently eat lunch and/or dinner every day