The saboteur within
When you embark on a positive change in any part of your life, it's fantastic to have the help and support of family and loved ones along the way. Unfortunately, however, this may not always be the case. In fact, it is not as uncommon as you might think for the people closest to those looking to change to sabotage any such plans or progress, consciously or otherwise.
For example, you might have planned a new and admirable start in terms of eating more healthily and/or exercising more while a romantic partner or family member may fear that any such change will disrupt the dynamic of the relationship. This could come in the form of said saboteur offering junk food or discouraging you from exercising or even making fun of your efforts.
The intention of such saboteurs can be reasoned through things like fear of change, being left behind in any healthy pursuit, anxiety through loss of control, guilt surrounding their own unhealthy habits or simply because breaking perceived bonding rituals (via comfort foods or shared meals) can bring about a perceived threat to intimacy.
Added to the above, from a historical perspective, food could be part of an important bonding ritual within the group and rejecting it or deviating from the norms could signal a test of group loyalty. Anyone standing out from the group could also be viewed with suspicion or jealousy.
So what are your options if faced with the difficulty of any such reaction to your efforts? One idea might be to frame changes less as an individual pursuit and more as a group effort. For example, including a partner in your goals might make them feel less excluded or threatened and as someone who has an important role to play. Trying the, "It would help me if we're all attempting to improve our habits as a team," approach is one option to try.
Replacing old rituals - like late-night snacking - with new ones could be another idea. Cooking a meal together as opposed to ordering take out might be a new weekend ritual, for example. Historically, rituals helped to signal belonging and safety and everyone had a role to play, no matter how big or small.
In short, sabotage can often come from fear of losing connection or balance. Transforming lifestyle changes into shared rituals and inclusive roles can help to reframe the old "don't upset the tribe" instinct into a "let's strengthen our tribe," one.