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Insulin under the influence of light -- ScienceDaily

To better assess the effect of light on tissue sensitivity to insulin, researchers measured insulin-induced glucose absorption. It turns out that a small disturbance in photic inputs (e.g. an hour of light exposure in the middle of the dark cycle, or light removal for 2 days) is enough to cause a negative effect. Indeed, increased or decreased light exposure can profoundly influence the sensitivity of tissues to insulin and the alteration, however minimal, of this mechanism is sufficient to significantly disrupt metabolic homeostasis. This would explain why people exposed to light at the wrong time -- workers in shift patterns, for example -- are more likely to develop metabolic diseases (e.g. diabetes).

Avocados, as a substitution for carbohydrates, can suppress hunger without adding calories: Meals that include fresh avocado can significantly suppress hunger and increase meal satisfaction -- ScienceDaily

The research found that meals including avocado not only resulted in a significant reduction in hunger and an increase in how satisfied participants felt, but also found that an intestinal hormone called PYY was an important messenger of the physiological response.

It's OK to indulge once in a while, study suggests: The body adapts to occasional short-term overeating: Body focuses on removing glucose to preserve insulin sensitivity in short-term overeating bout -- ScienceDaily

Although the amount of visceral fat that surrounds internal organs increased substantially, short-term overeating did not have a significant effect on the men's weight or fat mass. In addition, fasting levels of blood sugar and C-peptide -- an amino acid the body releases in response to increased production of insulin -- did not change. This finding was surprising because fasting levels of endogenous glucose -- new glucose the body produces in addition to what it has already stored for future use -- increased during the short-term trial. Chronic overeating increased the amount of total body fat and visceral fat as well as post-meal blood sugar and C-peptide levels. However, it did not alter fasting blood sugar levels, endogenous glucose production or the rate of glucose removal from the body (glucose disposal). This may be because the nutrient profile in the long-term trial was consistent with a typical diet and dietary fat percentages did not increase. Long-term overindulgence in fatty foods, instead of more nutritionally balanced foods, may be an important factor that causes rapid changes in blood sugar control.

How eating feeds into the body clock -- ScienceDaily

Dr Priya Crosby, a researcher at the MRC LMB and lead author on the study, highlighted: "Our data suggests that eating at the wrong times could have a major impact on our circadian rhythms. There is still work to do here, but paying particular attention to meal timing and light exposure is likely the best way to mitigate the adverse effects of shift-work. Even for those who work more traditional hours, being careful about when we eat is an important way to help maintain healthy body clocks, especially as we age."

Inactivity Induces Resistance to the Metabolic Benefits Following Acute Exercise. - PubMed - NCBI

METHODS: Ten untrained to recreationally active men (n=5) and women (n=5) completed a counterbalanced, crossover study. Four days of prolonged sitting without exercise (SIT) were compared to four days of prolonged sitting with a 1-hr bout of treadmill exercise (SIT+EX; 63.1±5.2% V̇O2max) on the evening of the fourth day. The following morning, participants completed a high fat/glucose tolerance test (HFGTT), during which plasma was collected over a 6-hr period and analyzed for triglycerides, glucose, and insulin. RESULTS: No differences between trials ( P > 0.05) were found in the overall plasma triglyceride, glucose, or insulin responses during the HFGTT. This lack of difference between trials comes with similarly low physical activity (~3,500-4,000 steps/day) on each day except for the 1-hr bout of exercise during SIT+EX the day before the HFGTT.

Seeing and smelling food prepares the mouse liver for digestion -- ScienceDaily

A previous study published in Cell in 2015 by another team of researchers found that sensory perception of food by lab mice was enough to trigger the neural pathways normally fueled by eating. Specifically, perceiving food inhibited AgRP neurons, which stimulate appetite, and activated POMC neurons, which induce satiety and suppress eating. The new study built on that research, focusing on how the changes in these neural pathways sent signals that affected metabolic activities in the liver. Here, the researchers found that within five minutes of lab mice perceiving food, the changes in POMC neuron activity were enough to induce a rapid signaling cascade that activated the mTOR and xbp1 signaling pathways. These pathways are normally activated when the liver takes up amino acids from digested food and help increase the protein folding capacity of the endoplasmic reticulum (ER), which assembles proteins from the amino acids found in food.

The case against carbohydrates gets stronger

We started the participants on a calorie-restricted diet until they lost 10%-14% of their body weight. After that, we randomly assigned them to eat exclusively one of three diets, containing either 20%, 40% or 60% carbohydrates. For the next five months, we made sure they didn’t gain or lose any more weight, adjusting how much food they received, but keeping the ratio of carbohydrates constant. By doing so, we could directly measure how their metabolism responded to these differing levels of carbohydrate consumption. Participants in the low (20%) carbohydrate group burned on average about 250 calories a day more than those in the high (60%) carbohydrate group, just as predicted by the carbohydrate-insulin model. Without intervention (that is, if we hadn’t adjusted the amount of food to prevent weight change), that difference would produce substantial weight loss — about 20 pounds after a few years. If a low-carbohydrate diet also curbs hunger and food intake (as other studies suggest it can), the effect could be even greater.

Insulin gives an extra boost to the immune system -- ScienceDaily

"We have identified one of metabolism's most popular hormones, specifically the insulin signaling pathway, as a novel 'co-stimulatory' driver of immune system function," says Dr. Dan Winer, who is also Assistant Professor, Department of Laboratory Medicine and Pathobiology at University of Toronto. "Our work characterizes the role of this signaling pathway in immune cells, mainly T cells, opening up avenues in the future to better regulate the immune system."