A few weeks back my inbox was jammed-packed with inquiries about the JAMA study that came out debunking Time Restricted Eating (TRE). What was my response?
I was not surprised at all!
Let’s look at the details of the study. The sample size was 116 participants who were allowed to eat as much as they wanted between the hours of 12 pm and 8 pm. There was no restriction on either the quality and balance of food (macronutrients – carbohydrate, protein, fat) or the quantity of food (calories).
If one truly wants to achieve a metabolic benefit, there needs to be changes to at least the balance of the diet. In other words, there is no free lunch and achieving metabolic results requires adjustments on multiple levels.
For example, what if you were eating a large pizza, an ice-cream sundae in those 8 hours? You would not expect to lose any type of weight and would probably gain weight.
It’s true that the less you expose your body to insulin, the faster your metabolism works if your food is balanced and tailored to your individual genetics. However, if you consume more sugars or carbs that your body can handle at any one time, your pancreas oversecretes insulin (i.e. works overtime). The amount of insulin released varies from 2x as high as 8000x the normal level of insulin a pancreas produces at any one time. That amount is dependent on many things – your genetic level of insulin resistance (i.e. carbohydrate sensitivity), and the amount and type of carbs you eat in a sitting.
Similar to eating a high sugar or carb meal, your pancreas can secrete 10x the amount of insulin it secretes at a low carb meal. The result? It can take your body 4-5 days to recover. During that time your metabolism will be sluggish, you may feel bloated, tired, crave more carbs and generally be out of sorts.
The take home message? If you are considering time restricted eating, you also have to match this window with a reasonable carbohydrate intake. A place to start might be 30 grams per 4 hours or per meal and adjust up or down as needed.
So yes – time restricted eating does work, when combined with a balanced diet that is tailored to your level of insulin resistance. Unfortunately, just as there is no free lunch, there is also no free carb limit.