We’ve all heard the claim that being ‘nil-by-mouth’ after 5pm helps you to lose weight, but is this really true?
Well, yes it is and here I’ll explain why and how eating later could be jeopardising your weight loss progress.
Reason #1: Artificial light causes insulin resistance
New research has shown that blue and green light, from devices and bright lighting, lead to chronically elevated stress hormone levels.
We should start the day with high cortisol that gradually decreases over the course of the day. Exposure to light in the evenings scews this pattern.
Chronically elevated cortisol is also associated with storage of fat around the middle and insulin resistance.
Insulin resistance is a state where your body is less responsive to the effects of insulin, meaning that you need more insulin to do the job of moving glucose into your cells.
Insulin is your fat storage hormone and therefore elevated insulin levels are not desirable!
Once the sun has gone down, you switch on artificial lighting and I think it’s safe to assume that most people are eating dinner in front of the TV or some sort of blue-light-emitting device.
Essentially, exposure to light when you’re supposed to be in darkness disrupts your circadian rhythm (your sleep-wake cycle) by increasing your stress hormone levels in the evening. We’ve known for a while that this affects sleep quality and duration, and that itself downregulates metabolism, but now we’re learning that this exposure to blue light also directly and immediately increases insulin resistance.
In light (pun not intended) of this recent research, eating during the hours of daylight may reduce insulin resistance and therefore aid your weight loss efforts.
Reason #2: The later you eat the shorter your fast
If you’ve read much of my content before, you’ll know that I’m big on fasting. The list of health and weight loss benefits are long.
I like my clients to have a minimum overnight fast (gap between dinner and breakfast) of at least 12 hours. During a fast, your blood sugar and insulin level decreases, allowing your body to move into fat-burning mode.
Ideally, this overnight fast should regularly last longer and sometimes it works well for people to have just two meals per day; so long as those meals are really nutrient-dense and balanced.
The later you eat, the shorter this overnight fast is and the less time you’ll spend in fat-burning mode (unless you delay breakfast).
Reason #3: The later you eat the less time you have to burn off carbs
For the majority, dinner involves starchy carbohydrates; potato, pasta, rice, bread, grains etc. Carbohydrates break down into glucose and are absorbed into the bloodstream and then into the cells for energy production.
Here’s the thing. In the evenings most people are pretty sedentary. There’s not a lot of energy being burned off after dinner. The earlier you eat, the more opportunity your body has to use any carbohydrates, that you ate at dinner, to make energy.
The later you eat, the more chance there is that your cells will be converting that glucose into fat for storage because you just don’t need the energy.
Summary Take home tips
Whilst not everyone that eats late will pile on the pounds, if you’re struggling to lose weight or reverse type-2 diabetes then it’s worth trying the following steps:
- When practical, avoid eating after dark
- Do not eat in front of a device like the TV or your phone
- After the sun has gone down, wear glasses that block blue light.
- If you have to eat late have a low-carb meal
- Eating two meals per day is perfectly okay and is often a helpful strategy for weight loss.
Sources:
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0155601
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3602916/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3107005/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3686562/
https://www.sciencedaily.com/releases/2018/06/180604172736.htm
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