Low Carbohydrate/High Protein Diet to Improve Metabolic Health

Individuals with spinal cord injury (SCI) are living to ages when metabolic disorders are
highly prevalent. Due to the loss of mobility and severe skeletal muscle atrophy in
individuals with SCI, obesity, impaired glucose tolerance, and peripheral insulin resistance
develop after injury . The combination of impaired glucose tolerance and insulin resistance
can disrupt lipid metabolism and increase the risk of cardiovascular disease and diabetes,
and contribute to an accelerated aging process in the SCI population. Because of these
trends, the overall burden of health complications and their economic impact has increased
for individuals with SCI, often leading to a progressive decrease in their long-term quality
of life. Feasible interventions to improve metabolic function (i.e. the way the body
processes proteins, carbohydrates, and fats in foods) in those with chronic SCI are in great
demand. Given that metabolic disorders severely compromise health outcomes and important
domains of quality of life, including participation in daily life and community living and
employment outcomes, targeted strategies to combat these morbidities are of paramount
importance. Compared to pharmacologic therapies, dietary modification is a more
cost-effective treatment option for reducing the risk of metabolic dysfunction that,
surprisingly, has not been rigorously investigated in people with SCI. Much like the general
U.S. population, individuals with SCI consume far more fat and carbohydrate than recommended
levels. High fat, high carbohydrate diets (western diet) have been associated with a higher
prevalence of obesity and metabolic disease as well as negative adaptations in the diversity
of gut bacteria (increased levels of harmful bacteria and reduced levels of beneficial
bacteria) that usually precedes the development of diabetes or insulin resistance. Therefore,
macronutrient (carbohydrate, protein, and fat) modification may be able to prevent or correct
the impaired metabolic state in persons with SCI. Diets composed of relatively high protein
and low carbohydrate have been shown to improve body composition (i.e., reduce body fat while
maintaining lean tissue) and metabolic profiles (i.e., increase in insulin sensitivity and
glucose tolerance) in diabetic, able bodied individuals who are obese or overweight. This
improvement is thought to be due to protein's: (i) effect on the sensation of feeling full
after eating food despite similar or lower energy intake; (ii) contribution to storage of
fat-free mass; and (iii) insulin sensitizing effect.

The investigators' pilot work supports this hypothesis in that we showed that 8 weeks of a
low carbohydrate/high-protein (LC-HP) diet significantly improved whole body insulin
sensitivity (WBIS) and glucose tolerance and decreased the amount of intra-abdominal fat in
six men with SCI and with either untreated type 2 diabetes or impaired glucose tolerance
(pre-diabetes). In addition to significant improvements in metabolic health, our pilot work
also successfully demonstrated the safety and feasibility of our approach. The lack of
adverse effects and the improvement in glucose control and insulin sensitivity in our study
participants with SCI prompted us to propose the current study involving both men and women
in order to determine the effects of the dietary protocol to treat type 2 diabetes or
impaired glucose tolerance in persons with chronic SCI. Thus, the investigators propose an
investigation to determine if 8 weeks of an LC/HP dietary intervention induces the
physiological adaptations necessary to improve metabolic function and body composition and
alter the diversity of gut bacteria in a large cohort of individuals with SCI. The ultimate
outcome of this project will be an effective diet program which can be easily and
economically implemented at home as a non-pharmacological means of achieving blood glucose
control for people with SCI and impaired glucose tolerance or untreated type 2 diabetes.

Inclusion Criteria:

- Between the ages of 18 and 60 years

- diagnosis of traumatic SCI at the cervical, thoracic, or lumbar level (C5-L2)
classified as American Spinal Cord Injury Association Classification (AIS) A, B, C, or
D

- Impaired glucose tolerance or untreated type 2 diabetes

- at least 3 years post-injury.

Exclusion Criteria:

- Pregnant women.

- Neurological (other than SCI), vascular and/or cardiac problems that may limit
function and interfere with testing procedures

- Patients with evidence of renal insufficiency and liver disease by history, physical
examination, and laboratory tests

- Patients with underlying pulmonary diseases